[Typing-sig] Re: Any way to express that a dict is expected to have a key(s) but don't care about other keys?

Any time we allow types to be specified outside of type annotations, it tends to create problems. The interpreter must evaluate them immediately even if `from __future__ import annotations` is used. TypeVar scoping is probably the biggest problem in this particular case. Depending on the architecture of the type checker, there can also be issues with circular type references for types passed as arguments to the class declaration. -Eric