Example in merge_union_of_records is a no-op

[ivirshup]

Which documentation?

Python docstrings

What needs to be documented?

In the example given, the result type is the same as the input type:

Quote from the docstring

Simplifies unions of records, e.g.

    >>> array = ak.Array([{"a": 1}, {"b": 2}])

into records of options, i.e.

    >>> ak.merge_union_of_records(array)
    <Array [{a: 1, b: None}, {a: None, ...}] type='2 * {a: ?int64, b: ?int64}'>

>>> import awkward as ak
>>> ak.Array([{"a": 1}, {"b": 2}]).type.show()
2 * {
    a: ?int64,
    b: ?int64
}
>>> ak.merge_union_of_records(ak.Array([{"a": 1}, {"b": 2}])).type.show()
2 * {
    a: ?int64,
    b: ?int64
}

[agoose77]

Gah, this is the reason for doctests. I made a last minute change here. Thanks for catching it!