The followed method is defined in the pubsub.py which is a python file in the site-package pubsub. When I try to use this, the pycharm tells me this is invalid syntax with an arrow pointing to '->'. I don't why and I have installed the pypubsub.
def getDefaultPublisher() -> Publisher:
"""
Get the Publisher instance created by default when this module
is imported. See the module doc for details about this instance.
"""
return _publisher