Lookup the public-facing port that is NAT-ed to ``private_port``.
        Identical to the ``docker port`` command.

        Args:
            container (str): The container to look up
            private_port (int): The private port to inspect

        Returns:
            (list of dict): The mapping for the host ports

        Raises:
            :py:class:`docker.errors.APIError`
                If the server returns an error.

        Example:
            .. code-block:: bash

                $ docker run -d -p 80:80 ubuntu:14.04 /bin/sleep 30
                7174d6347063a83f412fad6124c99cffd25ffe1a0807eb4b7f9cec76ac8cb43b

            .. code-block:: python

                >>> cli.port('7174d6347063', 80)
                [{'HostIp': '0.0.0.0', 'HostPort': '80'}]

def port(self, container, private_port):
        """
        Lookup the public-facing port that is NAT-ed to ``private_port``.
        Identical to the ``docker port`` command.

        Args:
            container (str): The container to look up
            private_port (int): The private port to inspect

        Returns:
            (list of dict): The mapping for the host ports

        Raises:
            :py:class:`docker.errors.APIError`
                If the server returns an error.

        Example:
            .. code-block:: bash

                $ docker run -d -p 80:80 ubuntu:14.04 /bin/sleep 30
                7174d6347063a83f412fad6124c99cffd25ffe1a0807eb4b7f9cec76ac8cb43b

            .. code-block:: python

                >>> cli.port('7174d6347063', 80)
                [{'HostIp': '0.0.0.0', 'HostPort': '80'}]
        """
        res = self._get(self._url("/containers/{0}/json", container))
        self._raise_for_status(res)
        json_ = res.json()
        private_port = str(private_port)
        h_ports = None

        # Port settings is None when the container is running with
        # network_mode=host.
        port_settings = json_.get('NetworkSettings', {}).get('Ports')
        if port_settings is None:
            return None

        if '/' in private_port:
            return port_settings.get(private_port)

        for protocol in ['tcp', 'udp', 'sctp']:
            h_ports = port_settings.get(private_port + '/' + protocol)
            if h_ports:
                break

        return h_ports