def removeListener(listener):
        """
        Remove a mailbox change listener

        @type listener: Any object previously added to and not removed from
            this mailbox as a listener.
        @param listener: The object to remove from the set of listeners.

        @raise ValueError: Raised when the given object is not a listener for
            this mailbox.
        """

        Remove a mailbox change listener

        @type listener: Any object previously added to and not removed from
            this mailbox as a listener.
        @param listener: The object to remove from the set of listeners.

        @raise ValueError: Raised when the given object is not a listener for
            this mailbox.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/interfaces.py