This is technically wrong. The documentation states that:
"Note that None may be returned if no handler handles the request
(though the default installed global OpenerDirector uses
UnknownHandler to ensure this never happens)."
This is super marginal and making it optional causes a few dozen
errors in an internal dropbox code base.
PR #2516 aimed to widen the accepted file argument to json.dump, but
since `IO` is invariant in its argument, it actually disallowed
passing binary files.
The __new__ method should suffice, and having both interferes with providing
a __new__ in namedtuples, which we want to do to fix
https://github.com/python/mypy/issues/1279.
`@trait` has special meaning to the experimental mypyc compiler,
slightly restricting the behavior of the class in exchange for
allowing it to be multiply inherited from.
add_argument's type argument was recently changed to be (approximately)
`Callable[[_Text], _T]`. Because of contravariant subtyping for functions,
this had the effect of requiring that add_argument *always*
be unicode, which is wrong.
Change it to be `Callable[[str], _T]`.
* Make {C,WIN,PY}FUNCTYPE's restype argument optional (for void returns)
* Make WinError return WindowsError
* Don't have Array explicitly inherit from Sized
(since inheriting from classes with different metaclasses causes problems,
and it is a protocol anyways)
* Have Array.__iter__ properly return an Iterator instead of an Iterable
Michael J. Sullivan