Effect.map can't handle generators

[Sune Debel]

map currently uses asyncio.iscoroutine to determine if the result of a continuation function must be awaited. When a continuation returns a generator `asyncio.iscoroutine mistakes this generator for a coroutine:

from pfun import success


def f(_):
    yield from [1, 2, 3]

success(0).map(f).run(None)  # TypeError: object generator can't be used in 'await' expression