def cancel():
        """
        Cancel the scheduled call.

        @raises twisted.internet.error.AlreadyCalled: if the call has already
            happened.
        @raises twisted.internet.error.AlreadyCancelled: if the call has already
            been cancelled.
        """

        Cancel the scheduled call.

        @raises twisted.internet.error.AlreadyCalled: if the call has already
            happened.
        @raises twisted.internet.error.AlreadyCancelled: if the call has already
            been cancelled.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py