Return True if the connection to the host and port is successful.

        @return: bool

def is_available(self):
        """
        Return True if the connection to the host and port is successful.

        @return: bool
        """
        if self.scheme in NOOP_PROTOCOLS:
            return True

        if not self.port:
            raise RuntimeError('port is required')

        s = socket.socket()
        try:
            s.connect((self.host, self.port))
        except Exception:
            return False
        else:
            return True