def connectUNIX(address, factory, timeout=30, checkPID=0):
    """
        Connect a client protocol to a UNIX socket.

        @param address: a path to a unix socket on the filesystem.

        @param factory: a L{twisted.internet.protocol.ClientFactory} instance

        @param timeout: number of seconds to wait before assuming the connection
            has failed.

        @param checkPID: if True, check for a pid file to verify that a server
            is listening.  If C{address} is a Linux abstract namespace path,
            this must be C{False}.

        @return: An object which provides L{IConnector}.
        """
