def _fromConnectedSocket(cls, fileDescriptor, addressFamily, factory,
                             reactor):
        """
        Create a new L{Server} based on an existing connected I{SOCK_STREAM}
        socket.

        Arguments are the same as to L{Server.__init__}, except where noted.

        @param fileDescriptor: An integer file descriptor associated with a
            connected socket.  The socket must be in non-blocking mode.  Any
            additional attributes desired, such as I{FD_CLOEXEC}, must also be
            set already.

        @param addressFamily: The address family (sometimes called I{domain})
            of the existing socket.  For example, L{socket.AF_INET}.

        @return: A new instance of C{cls} wrapping the socket given by
            C{fileDescriptor}.
        """
        addressType = address.IPv4Address
        if addressFamily == socket.AF_INET6:
            addressType = address.IPv6Address
        skt = socket.fromfd(fileDescriptor, addressFamily, socket.SOCK_STREAM)
        addr = _getpeername(skt)
        protocolAddr = addressType('TCP', *addr)
        localPort = skt.getsockname()[1]

        protocol = factory.buildProtocol(protocolAddr)
        if protocol is None:
            skt.close()
            return

        self = cls(skt, protocol, addr, None, addr[1], reactor)
        self.repstr = "<%s #%s on %s>" % (
            self.protocol.__class__.__name__, self.sessionno, localPort)
        protocol.makeConnection(self)
        return self

        Create a new L{Server} based on an existing connected I{SOCK_STREAM}
        socket.

        Arguments are the same as to L{Server.__init__}, except where noted.

        @param fileDescriptor: An integer file descriptor associated with a
            connected socket.  The socket must be in non-blocking mode.  Any
            additional attributes desired, such as I{FD_CLOEXEC}, must also be
            set already.

        @param addressFamily: The address family (sometimes called I{domain})
            of the existing socket.  For example, L{socket.AF_INET}.

        @return: A new instance of C{cls} wrapping the socket given by
            C{fileDescriptor}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/tcp.py