Add more stubs for redis-py

[brainix]

I've tested these stubs against my own project here:
brainix/pottery#221

The output is clean for all these new stubs when running $ mypy --strict.

[srittau]

Thanks! A few remarks below.

[srittau]

Since the result type depends on whether store is given, we should use overloads to choose the right type (most arguments omitted in the example for brevity):

@overload
def sort(
    self,
    name: _Key, 
    start: Optional[int] = ...,
    # etc.
    store: None = ...,
    groups: Optional[bool] = ...,
) -> List[bytes]: ...
@overload
def sort(
    self,
    name: _Key, 
    start: Optional[int] = ...,
    # etc. with default
    *,
    store: _Key,
    groups: Optional[bool] = ...,
) -> int: ...
@overload
def sort(
    self,
    name: _Key, 
    start: Optional[int],
    # etc. without default
    store: _Key,
    groups: Optional[bool] = ...,
) -> int: ...

Unfortunately we need to overloads for the second case, otherwise we'd have a syntax error.

[brainix]

Great catch. However, I'm a little stuck. Whenever I try to implement this solution, I get the following errors:

stubs/redis/client.pyi:190: error: Overloaded function signatures 1 and 2 overlap with incompatible return types
stubs/redis/client.pyi:190: error: Overloaded function signatures 1 and 3 overlap with incompatible return types

Any tips?

[srittau]

Hmm, I can't reproduce this here locally, although we sometimes need # type: ignore when overloading. Could you commit what you have so far? We squash merge anyway.