I've changed some instances of `Text` to `_Key` so that bytes will be
accepted as well. I'm not sure if they should be `_Str` instead. The
existing annotations seem to use a mix of the two. _Str is a better
reflection of what redis-py will accept (any arguments that it passes
through to the redis server can be _Str and it'll convert to bytes); but
passing an int or float where a key is expected may be a code smell.
