Find the interface through which a MAC can be reached.

        Args:
            mac_address (str): A MAC address in 'xx:xx:xx:xx:xx:xx' format.

        Returns:
            list[dict]: a list of mac table data.

        Raises:
            KeyError: if `mac_address` is not specified.

        Examples:
            >>> from pprint import pprint
            >>> import pynos.device
            >>> conn = ('10.24.39.211', '22')
            >>> auth = ('admin', 'password')
            >>> with pynos.device.Device(conn=conn, auth=auth) as dev:
            ...     x = dev.find_interface_by_mac(
            ...     mac_address='10:23:45:67:89:ab')
            ...     pprint(x) # doctest: +ELLIPSIS
            [{'interface'...'mac_address'...'state'...'type'...'vlan'...}]

def find_interface_by_mac(self, **kwargs):
        """Find the interface through which a MAC can be reached.

        Args:
            mac_address (str): A MAC address in 'xx:xx:xx:xx:xx:xx' format.

        Returns:
            list[dict]: a list of mac table data.

        Raises:
            KeyError: if `mac_address` is not specified.

        Examples:
            >>> from pprint import pprint
            >>> import pynos.device
            >>> conn = ('10.24.39.211', '22')
            >>> auth = ('admin', 'password')
            >>> with pynos.device.Device(conn=conn, auth=auth) as dev:
            ...     x = dev.find_interface_by_mac(
            ...     mac_address='10:23:45:67:89:ab')
            ...     pprint(x) # doctest: +ELLIPSIS
            [{'interface'...'mac_address'...'state'...'type'...'vlan'...}]
        """
        mac = kwargs.pop('mac_address')
        results = [x for x in self.mac_table if x['mac_address'] == mac]
        return results