def __init__(self, protocol, isServer, hostAddress=None, peerAddress=None):
        """
        @param protocol: This transport will deliver bytes to this protocol.
        @type protocol: L{IProtocol} provider

        @param isServer: C{True} if this is the accepting side of the
            connection, C{False} if it is the connecting side.
        @type isServer: L{bool}

        @param hostAddress: The value to return from C{getHost}.  L{None}
            results in a new L{FakeAddress} being created to use as the value.
        @type hostAddress: L{IAddress} provider or L{None}

        @param peerAddress: The value to return from C{getPeer}.  L{None}
            results in a new L{FakeAddress} being created to use as the value.
        @type peerAddress: L{IAddress} provider or L{None}
        """
        self.protocol = protocol
        self.isServer = isServer
        self.stream = []
        self.serial = self._nextserial()
        if hostAddress is None:
            hostAddress = FakeAddress()
        self.hostAddress = hostAddress
        if peerAddress is None:
            peerAddress = FakeAddress()
        self.peerAddress = peerAddress

        @param protocol: This transport will deliver bytes to this protocol.
        @type protocol: L{IProtocol} provider

        @param isServer: C{True} if this is the accepting side of the
            connection, C{False} if it is the connecting side.
        @type isServer: L{bool}

        @param hostAddress: The value to return from C{getHost}.  L{None}
            results in a new L{FakeAddress} being created to use as the value.
        @type hostAddress: L{IAddress} provider or L{None}

        @param peerAddress: The value to return from C{getPeer}.  L{None}
            results in a new L{FakeAddress} being created to use as the value.
        @type peerAddress: L{IAddress} provider or L{None}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/iosim.py