def __init__(self, host, port=PORT, transport="UDP", ttl=None,
                 hidden=False, received=None, rport=_absent, branch=None,
                 maddr=None, **kw):
        """
        Set parameters of this Via header. All arguments correspond to
        attributes of the same name.

        To maintain compatibility with old SIP
        code, the 'rport' argument is used to determine the values of
        C{rportRequested} and C{rportValue}. If None, C{rportRequested} is set
        to True. (The deprecated method for doing this is to pass True.) If an
        integer, C{rportValue} is set to the given value.

        Any arguments not explicitly named here are collected into the
        C{otherParams} dict.
        """
        self.transport = transport
        self.host = host
        self.port = port
        self.ttl = ttl
        self.hidden = hidden
        self.received = received
        if rport is True:
            warnings.warn(
                "rport=True is deprecated since Twisted 9.0.",
                DeprecationWarning,
                stacklevel=2)
            self.rportValue = None
            self.rportRequested = True
        elif rport is None:
            self.rportValue = None
            self.rportRequested = True
        elif rport is _absent:
            self.rportValue = None
            self.rportRequested = False
        else:
            self.rportValue = rport
            self.rportRequested = False

        self.branch = branch
        self.maddr = maddr
        self.otherParams = kw

        Set parameters of this Via header. All arguments correspond to
        attributes of the same name.

        To maintain compatibility with old SIP
        code, the 'rport' argument is used to determine the values of
        C{rportRequested} and C{rportValue}. If None, C{rportRequested} is set
        to True. (The deprecated method for doing this is to pass True.) If an
        integer, C{rportValue} is set to the given value.

        Any arguments not explicitly named here are collected into the
        C{otherParams} dict.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/protocols/sip.py