Python 3.6 types: Using variable before assignment [duplicate]
Forward references are just strings referring to the name (as it is visible in the module).
class MyContainer: def addMyItem(self, item: 'MyItem'): passclass MyItem: def __init__(self, container: 'MyContainer'): passIf you need to import the name from somewhere else (and you only need the name for type checking, or if it might cause a circular import), you can use
import typingif typing.TYPE_CHECKING: from foo import Thing