From 41d63ab51939a9bcfa0dee3a5f824201a212456e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Chapoton?=
 <chapoton@math.univ-lyon1.fr>
Date: Thu, 17 Nov 2016 21:43:33 +0100
Subject: [PATCH] trac 21887 undoing alias of __nonzero__ in pyx files

---
 src/sage/rings/asymptotic/asymptotic_ring.py         |  2 +-
 src/sage/rings/complex_arb.pyx                       |  4 +---
 src/sage/rings/complex_interval.pyx                  |  4 +---
 src/sage/rings/complex_mpc.pyx                       |  4 +---
 src/sage/rings/complex_number.pyx                    |  4 +---
 src/sage/rings/continued_fraction.py                 |  2 +-
 src/sage/rings/finite_rings/element_givaro.pyx       |  4 +---
 src/sage/rings/finite_rings/element_ntl_gf2e.pyx     |  4 +---
 src/sage/rings/finite_rings/element_pari_ffelt.pyx   |  3 +--
 src/sage/rings/finite_rings/integer_mod.pyx          | 12 +++---------
 src/sage/rings/fraction_field_element.pyx            |  4 +---
 .../rings/function_field/function_field_element.pyx  |  4 +---
 src/sage/rings/ideal.py                              |  2 +-
 src/sage/rings/integer.pyx                           |  4 +---
 src/sage/rings/laurent_series_ring_element.pyx       |  4 +---
 src/sage/rings/morphism.pyx                          |  4 +---
 src/sage/rings/number_field/number_field_element.pyx |  4 +---
 .../number_field/number_field_element_quadratic.pyx  |  4 +---
 src/sage/rings/padics/CA_template.pxi                |  2 +-
 src/sage/rings/padics/CR_template.pxi                |  2 +-
 src/sage/rings/padics/FM_template.pxi                |  2 +-
 src/sage/rings/polynomial/laurent_polynomial.pyx     |  4 +---
 .../rings/polynomial/multi_polynomial_element.py     |  2 +-
 .../polynomial/multi_polynomial_libsingular.pyx      |  4 +---
 src/sage/rings/polynomial/pbori.pyx                  |  4 +---
 src/sage/rings/polynomial/plural.pyx                 |  4 +---
 src/sage/rings/polynomial/polynomial_element.pyx     |  4 +---
 .../polynomial/polynomial_integer_dense_flint.pyx    |  4 +---
 .../rings/polynomial/polynomial_modn_dense_ntl.pyx   |  4 +---
 .../rings/polynomial/polynomial_rational_flint.pyx   |  4 +---
 src/sage/rings/polynomial/polynomial_template.pxi    |  2 +-
 .../rings/polynomial/skew_polynomial_element.pyx     |  4 +---
 src/sage/rings/power_series_poly.pyx                 |  4 +---
 src/sage/rings/power_series_ring_element.pyx         |  4 +---
 src/sage/rings/qqbar.py                              |  2 +-
 src/sage/rings/quotient_ring_element.py              |  2 +-
 src/sage/rings/rational.pyx                          |  6 ++----
 src/sage/rings/real_arb.pyx                          |  4 +---
 src/sage/rings/real_interval_absolute.pyx            |  4 +---
 src/sage/rings/real_lazy.pyx                         |  4 +---
 src/sage/rings/real_mpfi.pyx                         |  4 +---
 src/sage/rings/real_mpfr.pyx                         |  4 +---
 src/sage/rings/universal_cyclotomic_field.py         |  2 +-
 43 files changed, 46 insertions(+), 113 deletions(-)

diff --git a/src/sage/rings/asymptotic/asymptotic_ring.py b/src/sage/rings/asymptotic/asymptotic_ring.py
index fd25735f6a0..3d0f367fe08 100644
--- a/src/sage/rings/asymptotic/asymptotic_ring.py
+++ b/src/sage/rings/asymptotic/asymptotic_ring.py
@@ -803,7 +803,7 @@ def __bool__(self):
         """
         return bool(self._summands_)
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def __eq__(self, other):
         r"""
diff --git a/src/sage/rings/complex_arb.pyx b/src/sage/rings/complex_arb.pyx
index 6828eab8c16..a43dbf63c97 100644
--- a/src/sage/rings/complex_arb.pyx
+++ b/src/sage/rings/complex_arb.pyx
@@ -1402,7 +1402,7 @@ cdef class ComplexBall(RingElement):
         return (arb_is_nonzero(acb_realref(self.value))
                 or arb_is_nonzero(acb_imagref(self.value)))
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` iff this complex ball is not the zero ball, i.e. if the
         midpoint and radius of its real and imaginary parts are not all zero.
@@ -1427,8 +1427,6 @@ cdef class ComplexBall(RingElement):
         """
         return not acb_is_zero(self.value)
 
-    __nonzero__ =__bool__
-
     def is_exact(self):
         """
         Return ``True`` iff the radius of this ball is zero.
diff --git a/src/sage/rings/complex_interval.pyx b/src/sage/rings/complex_interval.pyx
index 61828eef54d..130ca1fa727 100644
--- a/src/sage/rings/complex_interval.pyx
+++ b/src/sage/rings/complex_interval.pyx
@@ -1389,7 +1389,7 @@ cdef class ComplexIntervalFieldElement(sage.structure.element.FieldElement):
         """
         raise TypeError("can't convert complex interval to complex")
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if ``self`` is not known to be exactly zero.
 
@@ -1408,8 +1408,6 @@ cdef class ComplexIntervalFieldElement(sage.structure.element.FieldElement):
         """
         return self.real().__bool__() or self.imag().__bool__()
 
-    __nonzero__ =__bool__
-
     cpdef _richcmp_(left, right, int op):
         r"""
         As with the real interval fields this never returns false positives.
diff --git a/src/sage/rings/complex_mpc.pyx b/src/sage/rings/complex_mpc.pyx
index aa9c88195a7..92e6ad9f700 100644
--- a/src/sage/rings/complex_mpc.pyx
+++ b/src/sage/rings/complex_mpc.pyx
@@ -1243,7 +1243,7 @@ cdef class MPComplexNumber(sage.structure.element.FieldElement):
             elif cim<0: return -1
             else: return 0
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if ``self`` is not zero.
 
@@ -1258,8 +1258,6 @@ cdef class MPComplexNumber(sage.structure.element.FieldElement):
         """
         return not (mpfr_zero_p(self.value.re) and mpfr_zero_p(self.value.im))
 
-    __nonzero__ =__bool__
-
     def is_square(self):
         r"""
         This function always returns true as `\CC` is algebraically closed.
diff --git a/src/sage/rings/complex_number.pyx b/src/sage/rings/complex_number.pyx
index cb68ef7e34d..beadf16b075 100644
--- a/src/sage/rings/complex_number.pyx
+++ b/src/sage/rings/complex_number.pyx
@@ -859,7 +859,7 @@ cdef class ComplexNumber(sage.structure.element.FieldElement):
                                       real_string, digit_precision_bound,
                                       imag_string, digit_precision_bound)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if ``self`` is not zero. This is an internal function;
         use :meth:`is_zero()` instead.
@@ -872,8 +872,6 @@ cdef class ComplexNumber(sage.structure.element.FieldElement):
         """
         return not (mpfr_zero_p(self.__re) and mpfr_zero_p(self.__im))
 
-    __nonzero__ =__bool__
-
     def prec(self):
         """
         Return precision of this complex number.
diff --git a/src/sage/rings/continued_fraction.py b/src/sage/rings/continued_fraction.py
index f3317a03188..89282a3ac3b 100644
--- a/src/sage/rings/continued_fraction.py
+++ b/src/sage/rings/continued_fraction.py
@@ -1003,7 +1003,7 @@ def __bool__(self):
         """
         return bool(self.quotient(0)) or self.quotient(1) is not Infinity
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def is_zero(self):
         r"""
diff --git a/src/sage/rings/finite_rings/element_givaro.pyx b/src/sage/rings/finite_rings/element_givaro.pyx
index dafd3c8e624..7e077bc6e97 100644
--- a/src/sage/rings/finite_rings/element_givaro.pyx
+++ b/src/sage/rings/finite_rings/element_givaro.pyx
@@ -926,7 +926,7 @@ cdef class FiniteField_givaroElement(FinitePolyExtElement):
         """
         return self.element
 
-    def __bool__(FiniteField_givaroElement self):
+    def __nonzero__(FiniteField_givaroElement self):
         r"""
         Return ``True`` if ``self != k(0)``.
 
@@ -941,8 +941,6 @@ cdef class FiniteField_givaroElement(FinitePolyExtElement):
         """
         return not self._cache.objectptr.isZero(self.element)
 
-    __nonzero__ =__bool__
-
     def is_one(FiniteField_givaroElement self):
         r"""
         Return ``True`` if ``self == k(1)``.
diff --git a/src/sage/rings/finite_rings/element_ntl_gf2e.pyx b/src/sage/rings/finite_rings/element_ntl_gf2e.pyx
index 19bad4bc1a6..b1ffd765c1e 100644
--- a/src/sage/rings/finite_rings/element_ntl_gf2e.pyx
+++ b/src/sage/rings/finite_rings/element_ntl_gf2e.pyx
@@ -574,7 +574,7 @@ cdef class FiniteField_ntl_gf2eElement(FinitePolyExtElement):
 
         return " + ".join(reversed(_repr))
 
-    def __bool__(FiniteField_ntl_gf2eElement self):
+    def __nonzero__(FiniteField_ntl_gf2eElement self):
         r"""
         Return ``True`` if ``self != k(0)``.
 
@@ -591,8 +591,6 @@ cdef class FiniteField_ntl_gf2eElement(FinitePolyExtElement):
         (<Cache_ntl_gf2e>self._parent._cache).F.restore()
         return not bool(GF2E_IsZero(self.x))
 
-    __nonzero__ =__bool__
-
     def is_one(FiniteField_ntl_gf2eElement self):
         r"""
         Return ``True`` if ``self == k(1)``.
diff --git a/src/sage/rings/finite_rings/element_pari_ffelt.pyx b/src/sage/rings/finite_rings/element_pari_ffelt.pyx
index 55dc48f9b10..a61d3e0b26d 100644
--- a/src/sage/rings/finite_rings/element_pari_ffelt.pyx
+++ b/src/sage/rings/finite_rings/element_pari_ffelt.pyx
@@ -560,8 +560,7 @@ cdef class FiniteFieldElement_pari_ffelt(FinitePolyExtElement):
         """
         return not bool(FF_equal0(self.val))
 
-    __bool__ = is_unit
-    __nonzero__ =__bool__
+    __nonzero__ = is_unit
 
     def __pos__(FiniteFieldElement_pari_ffelt self):
         """
diff --git a/src/sage/rings/finite_rings/integer_mod.pyx b/src/sage/rings/finite_rings/integer_mod.pyx
index 6e6b479c109..1b1d38852ae 100644
--- a/src/sage/rings/finite_rings/integer_mod.pyx
+++ b/src/sage/rings/finite_rings/integer_mod.pyx
@@ -1901,7 +1901,7 @@ cdef class IntegerMod_gmp(IntegerMod_abstract):
         """
         return mpz_cmp_si(self.value, 1) == 0
 
-    def __bool__(IntegerMod_gmp self):
+    def __nonzero__(IntegerMod_gmp self):
         """
         Returns ``True`` if this is not `0`, otherwise
         ``False``.
@@ -1915,8 +1915,6 @@ cdef class IntegerMod_gmp(IntegerMod_abstract):
         """
         return mpz_cmp_si(self.value, 0) != 0
 
-    __nonzero__ =__bool__
-
     cpdef bint is_unit(self):
         """
         Return True iff this element is a unit.
@@ -2299,7 +2297,7 @@ cdef class IntegerMod_int(IntegerMod_abstract):
         """
         return self.ivalue == 1
 
-    def __bool__(IntegerMod_int self):
+    def __nonzero__(IntegerMod_int self):
         """
         Returns ``True`` if this is not `0`, otherwise
         ``False``.
@@ -2313,8 +2311,6 @@ cdef class IntegerMod_int(IntegerMod_abstract):
         """
         return self.ivalue != 0
 
-    __nonzero__ =__bool__
-
     cpdef bint is_unit(IntegerMod_int self):
         """
         Return True iff this element is a unit
@@ -3118,7 +3114,7 @@ cdef class IntegerMod_int64(IntegerMod_abstract):
         """
         return self.ivalue == 1
 
-    def __bool__(IntegerMod_int64 self):
+    def __nonzero__(IntegerMod_int64 self):
         """
         Returns ``True`` if this is not `0`, otherwise
         ``False``.
@@ -3132,8 +3128,6 @@ cdef class IntegerMod_int64(IntegerMod_abstract):
         """
         return self.ivalue != 0
 
-    __nonzero__ =__bool__
-
     cpdef bint is_unit(IntegerMod_int64 self):
         """
         Return True iff this element is a unit.
diff --git a/src/sage/rings/fraction_field_element.pyx b/src/sage/rings/fraction_field_element.pyx
index a8a0d395c63..740ff078fd8 100644
--- a/src/sage/rings/fraction_field_element.pyx
+++ b/src/sage/rings/fraction_field_element.pyx
@@ -869,7 +869,7 @@ cdef class FractionFieldElement(FieldElement):
         """
         return self.__numerator.valuation(v) - self.__denominator.valuation(v)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if this element is nonzero.
 
@@ -888,8 +888,6 @@ cdef class FractionFieldElement(FieldElement):
         """
         return not self.__numerator.is_zero()
 
-    __nonzero__ =__bool__
-
     def is_zero(self):
         """
         Return ``True`` if this element is equal to zero.
diff --git a/src/sage/rings/function_field/function_field_element.pyx b/src/sage/rings/function_field/function_field_element.pyx
index b4c17de2df0..bb5f5997479 100644
--- a/src/sage/rings/function_field/function_field_element.pyx
+++ b/src/sage/rings/function_field/function_field_element.pyx
@@ -346,7 +346,7 @@ cdef class FunctionFieldElement_polymod(FunctionFieldElement):
         """
         return self._x._repr(name=self.parent().variable_name())
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         EXAMPLES::
 
@@ -361,8 +361,6 @@ cdef class FunctionFieldElement_polymod(FunctionFieldElement):
         """
         return not not self._x
 
-    __nonzero__ =__bool__
-
     def __hash__(self):
         """
         TESTS::
diff --git a/src/sage/rings/ideal.py b/src/sage/rings/ideal.py
index e8815a1718a..6fbf68e9867 100644
--- a/src/sage/rings/ideal.py
+++ b/src/sage/rings/ideal.py
@@ -419,7 +419,7 @@ def __bool__(self):
                 return True
         return False
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def base_ring(self):
         r"""
diff --git a/src/sage/rings/integer.pyx b/src/sage/rings/integer.pyx
index 9fc26138ce2..d7369cf3d66 100644
--- a/src/sage/rings/integer.pyx
+++ b/src/sage/rings/integer.pyx
@@ -4293,7 +4293,7 @@ cdef class Integer(sage.structure.element.EuclideanDomainElement):
         """
         return mpz_cmp_si(self.value, 1) == 0
 
-    def __bool__(self):
+    def __nonzero__(self):
         r"""
         Returns ``True`` if the integer is not `0`, otherwise ``False``.
 
@@ -4306,8 +4306,6 @@ cdef class Integer(sage.structure.element.EuclideanDomainElement):
         """
         return mpz_sgn(self.value) != 0
 
-    __nonzero__ =__bool__
-
     def is_integral(self):
         """
         Return ``True`` since integers are integral, i.e.,
diff --git a/src/sage/rings/laurent_series_ring_element.pyx b/src/sage/rings/laurent_series_ring_element.pyx
index e3ceded54cf..6c57351295e 100644
--- a/src/sage/rings/laurent_series_ring_element.pyx
+++ b/src/sage/rings/laurent_series_ring_element.pyx
@@ -221,11 +221,9 @@ cdef class LaurentSeries(AlgebraElement):
 
         return self.__u.is_monomial()
 
-    def __bool__(self):
+    def __nonzero__(self):
         return not not self.__u
 
-    __nonzero__ =__bool__
-
     def _im_gens_(self, codomain, im_gens):
         return codomain(self(im_gens[0]))
 
diff --git a/src/sage/rings/morphism.pyx b/src/sage/rings/morphism.pyx
index 7e25e0dfcfc..851408e69ad 100644
--- a/src/sage/rings/morphism.pyx
+++ b/src/sage/rings/morphism.pyx
@@ -602,7 +602,7 @@ cdef class RingHomomorphism(RingMap):
             raise TypeError("parent must be a ring homset")
         RingMap.__init__(self, parent)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Every ring map is nonzero unless the domain or codomain is the
         0 ring, since there is no zero map between rings, since 1 goes
@@ -626,8 +626,6 @@ cdef class RingHomomorphism(RingMap):
         """
         return bool(self.codomain().one())
 
-    __nonzero__ =__bool__
-
     def _repr_type(self):
         """
         Used internally in printing this morphism.
diff --git a/src/sage/rings/number_field/number_field_element.pyx b/src/sage/rings/number_field/number_field_element.pyx
index 7bfad4cbf14..cfecf3aec4a 100644
--- a/src/sage/rings/number_field/number_field_element.pyx
+++ b/src/sage/rings/number_field/number_field_element.pyx
@@ -2265,7 +2265,7 @@ cdef class NumberFieldElement(FieldElement):
         """
         return self._mul_(~right)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return True if this number field element is nonzero.
 
@@ -2284,8 +2284,6 @@ cdef class NumberFieldElement(FieldElement):
         """
         return not IsZero_ZZX(self.__numerator)
 
-    __nonzero__ =__bool__
-
     cpdef _neg_(self):
         r"""
         EXAMPLE::
diff --git a/src/sage/rings/number_field/number_field_element_quadratic.pyx b/src/sage/rings/number_field/number_field_element_quadratic.pyx
index 0a5950ce158..efdcec9b6fc 100644
--- a/src/sage/rings/number_field/number_field_element_quadratic.pyx
+++ b/src/sage/rings/number_field/number_field_element_quadratic.pyx
@@ -1317,7 +1317,7 @@ cdef class NumberFieldElement_quadratic(NumberFieldElement_absolute):
         h += 42082631 * mpz_pythonhash(self.b)
         return h
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Check whether this element is not zero.
 
@@ -1331,8 +1331,6 @@ cdef class NumberFieldElement_quadratic(NumberFieldElement_absolute):
         """
         return mpz_cmp_ui(self.a, 0) != 0 or mpz_cmp_ui(self.b, 0) != 0
 
-    __nonzero__ =__bool__
-
     def _integer_(self, Z=None):
         """
         EXAMPLES:
diff --git a/src/sage/rings/padics/CA_template.pxi b/src/sage/rings/padics/CA_template.pxi
index c87b7fd9351..d998b2100e5 100644
--- a/src/sage/rings/padics/CA_template.pxi
+++ b/src/sage/rings/padics/CA_template.pxi
@@ -621,7 +621,7 @@ cdef class CAElement(pAdicTemplateElement):
         """
         return not ciszero(self.value, self.prime_pow)
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def is_equal_to(self, _right, absprec=None):
         r"""
diff --git a/src/sage/rings/padics/CR_template.pxi b/src/sage/rings/padics/CR_template.pxi
index cb307c21ad3..84bd7b0180f 100644
--- a/src/sage/rings/padics/CR_template.pxi
+++ b/src/sage/rings/padics/CR_template.pxi
@@ -975,7 +975,7 @@ cdef class CRElement(pAdicTemplateElement):
         """
         return self.relprec != 0
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def is_equal_to(self, _right, absprec=None):
         r"""
diff --git a/src/sage/rings/padics/FM_template.pxi b/src/sage/rings/padics/FM_template.pxi
index 22d644513e6..fe34389fe84 100644
--- a/src/sage/rings/padics/FM_template.pxi
+++ b/src/sage/rings/padics/FM_template.pxi
@@ -497,7 +497,7 @@ cdef class FMElement(pAdicTemplateElement):
         """
         return not ciszero(self.value, self.prime_pow)
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def is_equal_to(self, _right, absprec=None):
         r"""
diff --git a/src/sage/rings/polynomial/laurent_polynomial.pyx b/src/sage/rings/polynomial/laurent_polynomial.pyx
index b6ffd69fbf7..8e4ffc2e2c7 100644
--- a/src/sage/rings/polynomial/laurent_polynomial.pyx
+++ b/src/sage/rings/polynomial/laurent_polynomial.pyx
@@ -161,7 +161,7 @@ cdef class LaurentPolynomial_univariate(LaurentPolynomial_generic):
         """
         return self.__u.is_zero()
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Check if ``self`` is non-zero.
 
@@ -177,8 +177,6 @@ cdef class LaurentPolynomial_univariate(LaurentPolynomial_generic):
         """
         return not self.__u.is_zero()
 
-    __nonzero__ =__bool__
-
     def _im_gens_(self, codomain, im_gens):
         """
         Return the image of ``self`` under the morphism defined by
diff --git a/src/sage/rings/polynomial/multi_polynomial_element.py b/src/sage/rings/polynomial/multi_polynomial_element.py
index 8f769df553a..7ca1bd6c46c 100644
--- a/src/sage/rings/polynomial/multi_polynomial_element.py
+++ b/src/sage/rings/polynomial/multi_polynomial_element.py
@@ -1474,7 +1474,7 @@ def __bool__(self):
         """
         return self._MPolynomial_element__element.dict()!={}
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def _floordiv_(self, right):
         r"""
diff --git a/src/sage/rings/polynomial/multi_polynomial_libsingular.pyx b/src/sage/rings/polynomial/multi_polynomial_libsingular.pyx
index 5ff7f128af8..81f64bb3e57 100644
--- a/src/sage/rings/polynomial/multi_polynomial_libsingular.pyx
+++ b/src/sage/rings/polynomial/multi_polynomial_libsingular.pyx
@@ -3888,7 +3888,7 @@ cdef class MPolynomial_libsingular(sage.rings.polynomial.multi_polynomial.MPolyn
         else:
             return False
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         EXAMPLES::
 
@@ -3903,8 +3903,6 @@ cdef class MPolynomial_libsingular(sage.rings.polynomial.multi_polynomial.MPolyn
         else:
             return False
 
-    __nonzero__ =__bool__
-
     cpdef _floordiv_(self, right):
         """
         Perform division with remainder and return the quotient.
diff --git a/src/sage/rings/polynomial/pbori.pyx b/src/sage/rings/polynomial/pbori.pyx
index 685514abd85..49c1a23213d 100644
--- a/src/sage/rings/polynomial/pbori.pyx
+++ b/src/sage/rings/polynomial/pbori.pyx
@@ -3532,7 +3532,7 @@ cdef class BooleanPolynomial(MPolynomial):
         """
         return self._pbpoly.isZero()
 
-    def __bool__(self):
+    def __nonzero__(self):
         r"""
         Check if ``self`` is zero.
 
@@ -3554,8 +3554,6 @@ cdef class BooleanPolynomial(MPolynomial):
         """
         return not self._pbpoly.isZero()
 
-    __nonzero__ =__bool__
-
     def is_one(BooleanPolynomial self):
         """
         Check if self is 1.
diff --git a/src/sage/rings/polynomial/plural.pyx b/src/sage/rings/polynomial/plural.pyx
index f048791bf59..83d632afc45 100644
--- a/src/sage/rings/polynomial/plural.pyx
+++ b/src/sage/rings/polynomial/plural.pyx
@@ -2629,7 +2629,7 @@ cdef class NCPolynomial_plural(RingElement):
         else:
             return False
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         EXAMPLES::
 
@@ -2648,8 +2648,6 @@ cdef class NCPolynomial_plural(RingElement):
         else:
             return False
 
-    __nonzero__ =__bool__
-
 
 #####################################################################
 
diff --git a/src/sage/rings/polynomial/polynomial_element.pyx b/src/sage/rings/polynomial/polynomial_element.pyx
index 9aaa77043c6..8b5c0f475c2 100644
--- a/src/sage/rings/polynomial/polynomial_element.pyx
+++ b/src/sage/rings/polynomial/polynomial_element.pyx
@@ -930,7 +930,7 @@ cdef class Polynomial(CommutativeAlgebraElement):
             if c: return c
         return 0
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         EXAMPLES::
 
@@ -943,8 +943,6 @@ cdef class Polynomial(CommutativeAlgebraElement):
         """
         return self.degree() >= 0
 
-    __nonzero__ =__bool__
-
     def __getitem__(self, n):
         r"""
         Return the `n`-th coefficient of ``self``.
diff --git a/src/sage/rings/polynomial/polynomial_integer_dense_flint.pyx b/src/sage/rings/polynomial/polynomial_integer_dense_flint.pyx
index 1f62a0f0b78..9524badf1e1 100644
--- a/src/sage/rings/polynomial/polynomial_integer_dense_flint.pyx
+++ b/src/sage/rings/polynomial/polynomial_integer_dense_flint.pyx
@@ -749,7 +749,7 @@ cdef class Polynomial_integer_dense_flint(Polynomial):
         """
         return (fmpz_poly_degree(self.__poly) == -1)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Check if self is not zero.
 
@@ -765,8 +765,6 @@ cdef class Polynomial_integer_dense_flint(Polynomial):
         """
         return not (fmpz_poly_degree(self.__poly) == -1)
 
-    __nonzero__ =__bool__
-
     @coerce_binop
     def gcd(self, right):
         r"""
diff --git a/src/sage/rings/polynomial/polynomial_modn_dense_ntl.pyx b/src/sage/rings/polynomial/polynomial_modn_dense_ntl.pyx
index 460026f8d9b..afac91cad43 100644
--- a/src/sage/rings/polynomial/polynomial_modn_dense_ntl.pyx
+++ b/src/sage/rings/polynomial/polynomial_modn_dense_ntl.pyx
@@ -1043,7 +1043,7 @@ cdef class Polynomial_dense_modn_ntl_zz(Polynomial_dense_mod_n):
     def is_gen(self):
         return zz_pX_IsX(self.x)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         TESTS::
 
@@ -1056,8 +1056,6 @@ cdef class Polynomial_dense_modn_ntl_zz(Polynomial_dense_mod_n):
         """
         return not zz_pX_IsZero(self.x)
 
-    __nonzero__ =__bool__
-
     def valuation(self):
         """
         Returns the valuation of self, that is, the power of the
diff --git a/src/sage/rings/polynomial/polynomial_rational_flint.pyx b/src/sage/rings/polynomial/polynomial_rational_flint.pyx
index 4a63dd57e98..b6c1b25e7cb 100644
--- a/src/sage/rings/polynomial/polynomial_rational_flint.pyx
+++ b/src/sage/rings/polynomial/polynomial_rational_flint.pyx
@@ -712,7 +712,7 @@ cdef class Polynomial_rational_flint(Polynomial):
         """
         return fmpq_poly_is_one(self.__poly)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Returns whether or not self is non-zero.
 
@@ -727,8 +727,6 @@ cdef class Polynomial_rational_flint(Polynomial):
         """
         return not fmpq_poly_is_zero(self.__poly)
 
-    __nonzero__ =__bool__
-
     ###########################################################################
     # Shifting                                                                #
     ###########################################################################
diff --git a/src/sage/rings/polynomial/polynomial_template.pxi b/src/sage/rings/polynomial/polynomial_template.pxi
index 8cd2ba5838a..240de65c086 100644
--- a/src/sage/rings/polynomial/polynomial_template.pxi
+++ b/src/sage/rings/polynomial/polynomial_template.pxi
@@ -529,7 +529,7 @@ cdef class Polynomial_template(Polynomial):
         """
         return not celement_is_zero(&self.x, (<Polynomial_template>self)._cparent)
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     cpdef int _cmp_(left, right) except -2:
         """
diff --git a/src/sage/rings/polynomial/skew_polynomial_element.pyx b/src/sage/rings/polynomial/skew_polynomial_element.pyx
index a139662a7a0..ed28dfbe47f 100644
--- a/src/sage/rings/polynomial/skew_polynomial_element.pyx
+++ b/src/sage/rings/polynomial/skew_polynomial_element.pyx
@@ -1675,7 +1675,7 @@ cdef class SkewPolynomial(AlgebraElement):
         return (self.degree() == self.valuation() and
                 self.leading_coefficient()._is_atomic())
 
-    def __bool__(self):
+    def __nonzero__(self):
         r"""
         Test whether ``self`` is nonzero.
 
@@ -1693,8 +1693,6 @@ cdef class SkewPolynomial(AlgebraElement):
         """
         return not self.is_zero()
 
-    __nonzero__ =__bool__
-
     def base_ring(self):
         r"""
         Return the base ring of ``self``.
diff --git a/src/sage/rings/power_series_poly.pyx b/src/sage/rings/power_series_poly.pyx
index 5bec0b1434a..09d5c341acc 100644
--- a/src/sage/rings/power_series_poly.pyx
+++ b/src/sage/rings/power_series_poly.pyx
@@ -140,7 +140,7 @@ cdef class PowerSeries_poly(PowerSeries):
         """
         return self.__f.degree()
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return True if self is nonzero, and False otherwise.
 
@@ -156,8 +156,6 @@ cdef class PowerSeries_poly(PowerSeries):
         """
         return not not self.__f
 
-    __nonzero__ =__bool__
-
     def __call__(self, *x, **kwds):
         """
         Evaluate the series at x=a.
diff --git a/src/sage/rings/power_series_ring_element.pyx b/src/sage/rings/power_series_ring_element.pyx
index 8feec98b14e..77c12ec97aa 100644
--- a/src/sage/rings/power_series_ring_element.pyx
+++ b/src/sage/rings/power_series_ring_element.pyx
@@ -906,7 +906,7 @@ cdef class PowerSeries(AlgebraElement):
         # endif
         return prec
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return True if this power series is not equal to 0.
 
@@ -926,8 +926,6 @@ cdef class PowerSeries(AlgebraElement):
         """
         return not not self.polynomial()
 
-    __nonzero__ =__bool__
-
     def is_unit(self):
         """
         Return True if this power series is invertible.
diff --git a/src/sage/rings/qqbar.py b/src/sage/rings/qqbar.py
index 636a0212a8b..f43e8bdeeda 100644
--- a/src/sage/rings/qqbar.py
+++ b/src/sage/rings/qqbar.py
@@ -3834,7 +3834,7 @@ def __bool__(self):
         self.exactify()
         return self.__bool__()
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def __pow__(self, e):
         r""" ``self**p`` returns the `p`'th power of self (where `p` can
diff --git a/src/sage/rings/quotient_ring_element.py b/src/sage/rings/quotient_ring_element.py
index a2eadebf625..b3866dc8f1e 100644
--- a/src/sage/rings/quotient_ring_element.py
+++ b/src/sage/rings/quotient_ring_element.py
@@ -148,7 +148,7 @@ def __bool__(self):
         """
         return self.__rep not in self.parent().defining_ideal()
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def is_unit(self):
         """
diff --git a/src/sage/rings/rational.pyx b/src/sage/rings/rational.pyx
index 08da03bb94c..a76e802377c 100644
--- a/src/sage/rings/rational.pyx
+++ b/src/sage/rings/rational.pyx
@@ -16,7 +16,7 @@ AUTHORS:
 - David Harvey (2006-09-15): added nth_root
 
 - Pablo De Napoli (2007-04-01): corrected the implementations of
-  multiplicative_order, is_one; optimized __bool__ ; documented:
+  multiplicative_order, is_one; optimized __nonzero__ ; documented:
   lcm,gcd
 
 - John Cremona (2009-05-15): added support for local and global
@@ -2551,7 +2551,7 @@ cdef class Rational(sage.structure.element.FieldElement):
         mpq_neg(x.value, self.value)
         return x
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if this rational number is nonzero.
 
@@ -2567,8 +2567,6 @@ cdef class Rational(sage.structure.element.FieldElement):
         # A rational number is zero iff its numerator is zero.
         return mpq_sgn(self.value) != 0
 
-    __nonzero__ =__bool__
-
     def __abs__(self):
         """
         Return the absolute value of this rational number.
diff --git a/src/sage/rings/real_arb.pyx b/src/sage/rings/real_arb.pyx
index 391c0dd477c..7b42a18e89a 100644
--- a/src/sage/rings/real_arb.pyx
+++ b/src/sage/rings/real_arb.pyx
@@ -2006,7 +2006,7 @@ cdef class RealBall(RingElement):
         """
         return arb_is_nonzero(self.value)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` iff this ball is not the zero ball, i.e. if it its
         midpoint and radius are not both zero.
@@ -2031,8 +2031,6 @@ cdef class RealBall(RingElement):
         """
         return not arb_is_zero(self.value)
 
-    __nonzero__ =__bool__
-
     def is_exact(self):
         """
         Return ``True`` iff the radius of this ball is zero.
diff --git a/src/sage/rings/real_interval_absolute.pyx b/src/sage/rings/real_interval_absolute.pyx
index 0a1479c13df..ec9f72afc39 100644
--- a/src/sage/rings/real_interval_absolute.pyx
+++ b/src/sage/rings/real_interval_absolute.pyx
@@ -567,7 +567,7 @@ cdef class RealIntervalAbsoluteElement(FieldElement):
     cdef bint is_exact(self):
         return not self._diameter
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` for anything except exact zero.
 
@@ -584,8 +584,6 @@ cdef class RealIntervalAbsoluteElement(FieldElement):
         """
         return not not self._mantissa or not not self._diameter
 
-    __nonzero__ =__bool__
-
     def __neg__(self):
         """
         TESTS::
diff --git a/src/sage/rings/real_lazy.pyx b/src/sage/rings/real_lazy.pyx
index caa30177ccb..26542878f33 100644
--- a/src/sage/rings/real_lazy.pyx
+++ b/src/sage/rings/real_lazy.pyx
@@ -988,7 +988,7 @@ cdef class LazyWrapper(LazyFieldElement):
         """
         return <double>self._value
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Check to see if ``self`` is not zero.
 
@@ -1002,8 +1002,6 @@ cdef class LazyWrapper(LazyFieldElement):
         """
         return not not self._value
 
-    __nonzero__ =__bool__
-
     def __hash__(self):
         """
         Return the hash value of ``self``.
diff --git a/src/sage/rings/real_mpfi.pyx b/src/sage/rings/real_mpfi.pyx
index 259bded4c93..3b5e77d40b5 100644
--- a/src/sage/rings/real_mpfi.pyx
+++ b/src/sage/rings/real_mpfi.pyx
@@ -3731,7 +3731,7 @@ cdef class RealIntervalFieldElement(RingElement):
         elif op == 5: #>=
             return mpfr_lessequal_p(&rt.value.right, &lt.value.left)
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if ``self`` is not known to be exactly zero.
 
@@ -3750,8 +3750,6 @@ cdef class RealIntervalFieldElement(RingElement):
         """
         return not (mpfr_zero_p(&self.value.left) and mpfr_zero_p(&self.value.right))
 
-    __nonzero__ =__bool__
-
     cpdef int _cmp_(left, right) except -2:
         """
         Compare two intervals lexicographically.
diff --git a/src/sage/rings/real_mpfr.pyx b/src/sage/rings/real_mpfr.pyx
index a2388fc63b3..52c81d50457 100644
--- a/src/sage/rings/real_mpfr.pyx
+++ b/src/sage/rings/real_mpfr.pyx
@@ -3784,7 +3784,7 @@ cdef class RealNumber(sage.structure.element.RingElement):
         """
         return mpfr_integer_p(self.value) != 0
 
-    def __bool__(self):
+    def __nonzero__(self):
         """
         Return ``True`` if ``self`` is nonzero.
 
@@ -3808,8 +3808,6 @@ cdef class RealNumber(sage.structure.element.RingElement):
         """
         return not mpfr_zero_p(self.value)
 
-    __nonzero__ =__bool__
-
     cpdef int _cmp_(left, right) except -2:
         """
         Return ``-1`` if exactly one of the numbers is ``NaN``.  Return ``-1``
diff --git a/src/sage/rings/universal_cyclotomic_field.py b/src/sage/rings/universal_cyclotomic_field.py
index 19f5d5679a4..ab170248cfa 100644
--- a/src/sage/rings/universal_cyclotomic_field.py
+++ b/src/sage/rings/universal_cyclotomic_field.py
@@ -285,7 +285,7 @@ def __bool__(self):
         """
         return bool(self._obj)
 
-    __nonzero__ =__bool__
+    __nonzero__ = __bool__
 
     def __reduce__(self):
         r"""