def addReader(reader):
        """
        I add reader to the set of file descriptors to get read events for.

        @param reader: An L{IReadDescriptor} provider that will be checked for
                       read events until it is removed from the reactor with
                       L{removeReader}.

        @return: L{None}.
        """

        I add reader to the set of file descriptors to get read events for.

        @param reader: An L{IReadDescriptor} provider that will be checked for
                       read events until it is removed from the reactor with
                       L{removeReader}.

        @return: L{None}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/interfaces.py