def cancel_port_forward(self, address, port):
if not self.active:<EOL><INDENT>return<EOL><DEDENT>self._tcp_handler = None<EOL>self.global_request('<STR_LIT>', (address, port), wait=True)<EOL>
Ask the server to cancel a previous port-forwarding request.  No more
connections to the given address & port will be forwarded across this
ssh connection.

@param address: the address to stop forwarding
@type address: str
@param port: the port to stop forwarding
@type port: int