Rename 'next' to 'anext' on Response

[florimondmanca]

Refs #667

[florimondmanca]

Yes, that's surprising, and possibly related to python/cpython#16600 — details below…

Details (click to expand)

Essentially boils down to…

import inspect

class Foo:
    async def bar(self):
        pass

foo = Foo()
bar = functools.partial(foo.bar)
print(inspect.iscoroutinefunction(bar))  # False

Strangely though, the non-partial'd method behaves just fine…

print(inspect.iscoroutinefunction(foo.bar))  # True

functools.partial is definitely doing something weird here, because…

print(functools._unwrap_partial(bar) is foo.bar)  # False

Even though the unwrapping returns the same underlying function for "non-method" functions…

async def funcbar():
    pass

pfuncbar = functools.partial(funcbar)
print(functools._unwrap_partial(pfuncbar) is funcbar)  # True

But then I realized this is a property of bound methods themselves…

print(foo.bar is foo.bar)  # False

Wtf, Python? 🤷‍♂🤷‍♂🤷‍♂🤷‍♂🤷‍♂

[florimondmanca]

Strangely, this workaround doesn't work on 3.6 and 3.7 — CI is failing for those versions. 😕