def __init__(self, port, proto, interface='', maxPacketSize=8192, reactor=None):
        """
        @param port: A port number on which to listen.
        @type port: L{int}

        @param proto: A C{DatagramProtocol} instance which will be
            connected to the given C{port}.
        @type proto: L{twisted.internet.protocol.DatagramProtocol}

        @param interface: The local IPv4 or IPv6 address to which to bind;
            defaults to '', ie all IPv4 addresses.
        @type interface: L{str}

        @param maxPacketSize: The maximum packet size to accept.
        @type maxPacketSize: L{int}

        @param reactor: A reactor which will notify this C{Port} when
            its socket is ready for reading or writing. Defaults to
            L{None}, ie the default global reactor.
        @type reactor: L{interfaces.IReactorFDSet}
        """
        base.BasePort.__init__(self, reactor)
        self.port = port
        self.protocol = proto
        self.maxPacketSize = maxPacketSize
        self.interface = interface
        self.setLogStr()
        self._connectedAddr = None
        self._setAddressFamily()

        @param port: A port number on which to listen.
        @type port: L{int}

        @param proto: A C{DatagramProtocol} instance which will be
            connected to the given C{port}.
        @type proto: L{twisted.internet.protocol.DatagramProtocol}

        @param interface: The local IPv4 or IPv6 address to which to bind;
            defaults to '', ie all IPv4 addresses.
        @type interface: L{str}

        @param maxPacketSize: The maximum packet size to accept.
        @type maxPacketSize: L{int}

        @param reactor: A reactor which will notify this C{Port} when
            its socket is ready for reading or writing. Defaults to
            L{None}, ie the default global reactor.
        @type reactor: L{interfaces.IReactorFDSet}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/udp.py