Small cleanups to creating a ClientRequest

aiohttp/client_reqrep.py

@@ -25,7 +25,6 @@
     Tuple,
     Type,
     Union,
-    cast,
 )
 
 from multidict import CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy
@@ -227,17 +226,20 @@ def __init__(
         trust_env: bool = False,
         server_hostname: Optional[str] = None,
     ):
-        match = _CONTAINS_CONTROL_CHAR_RE.search(method)
-        if match:
+        if match := _CONTAINS_CONTROL_CHAR_RE.search(method):
             raise ValueError(
                 f"Method cannot contain non-token characters {method!r} "
                 f"(found at least {match.group()!r})"
             )
-        assert isinstance(url, URL), url
-        assert isinstance(proxy, (URL, type(None))), proxy
+        # URL forbids subclasses, so a simple type check is enough.
+        assert type(url) is URL, url
+        if proxy is not None:
+            assert type(proxy) is URL, proxy
         # FIXME: session is None in tests only, need to fix tests
         # assert session is not None
-        self._session = cast("ClientSession", session)
+        if TYPE_CHECKING:
+            assert session is not None
+        self._session = session
         if params:
             url = url.extend_query(params)
         self.original_url = url
@@ -271,9 +273,7 @@ def __init__(
         if data is not None or self.method not in self.GET_METHODS:
             self.update_transfer_encoding()
         self.update_expect_continue(expect100)
-        if traces is None:
-            traces = []
-        self._traces = traces
+        self._traces = [] if traces is None else traces
 
     def __reset_writer(self, _: object = None) -> None:
         self.__writer = None