Set interface description.

        Args:
            int_type (str): Type of interface. (gigabitethernet,
                tengigabitethernet, etc)
            name (str): Name of interface. (1/0/5, 1/0/10, etc)
            desc (str): The description of the interface.
            callback (function): A function executed upon completion of the
                method.  The only parameter passed to `callback` will be the
                ``ElementTree`` `config`.

        Returns:
            Return value of `callback`.

        Raises:
            KeyError: if `int_type`, `name`, or `desc` is not specified.
            ValueError: if `name`, `int_type`, or `desc` is not a valid
                value.

        Examples:
            >>> import pynos.device
            >>> switches = ['10.24.39.211', '10.24.39.203']
            >>> auth = ('admin', 'password')
            >>> for switch in switches:
            ...     conn = (switch, '22')
            ...     with pynos.device.Device(conn=conn, auth=auth) as dev:
            ...         output = dev.interface.description(
            ...         int_type='tengigabitethernet',
            ...         name='225/0/38',
            ...         desc='test')
            ...         dev.interface.description()
            ...         # doctest: +IGNORE_EXCEPTION_DETAIL
            Traceback (most recent call last):
            KeyError

def description(self, **kwargs):
        """Set interface description.

        Args:
            int_type (str): Type of interface. (gigabitethernet,
                tengigabitethernet, etc)
            name (str): Name of interface. (1/0/5, 1/0/10, etc)
            desc (str): The description of the interface.
            callback (function): A function executed upon completion of the
                method.  The only parameter passed to `callback` will be the
                ``ElementTree`` `config`.

        Returns:
            Return value of `callback`.

        Raises:
            KeyError: if `int_type`, `name`, or `desc` is not specified.
            ValueError: if `name`, `int_type`, or `desc` is not a valid
                value.

        Examples:
            >>> import pynos.device
            >>> switches = ['10.24.39.211', '10.24.39.203']
            >>> auth = ('admin', 'password')
            >>> for switch in switches:
            ...     conn = (switch, '22')
            ...     with pynos.device.Device(conn=conn, auth=auth) as dev:
            ...         output = dev.interface.description(
            ...         int_type='tengigabitethernet',
            ...         name='225/0/38',
            ...         desc='test')
            ...         dev.interface.description()
            ...         # doctest: +IGNORE_EXCEPTION_DETAIL
            Traceback (most recent call last):
            KeyError
        """
        int_type = str(kwargs.pop('int_type').lower())
        name = str(kwargs.pop('name'))
        desc = str(kwargs.pop('desc'))
        callback = kwargs.pop('callback', self._callback)

        int_types = [
            'gigabitethernet',
            'tengigabitethernet',
            'fortygigabitethernet',
            'hundredgigabitethernet',
            'port_channel',
            'vlan'
        ]

        if int_type not in int_types:
            raise ValueError("`int_type` must be one of: %s" % repr(int_types))

        desc_args = dict(name=name, description=desc)

        if int_type == "vlan":
            if not pynos.utilities.valid_vlan_id(name):
                raise InvalidVlanId("`name` must be between `1` and `8191`")

            config = self._interface.interface_vlan_interface_vlan_description(
                **desc_args
            )
        else:
            if not pynos.utilities.valid_interface(int_type, name):
                raise ValueError('`name` must be in the format of x/y/z for '
                                 'physical interfaces or x for port channel.')

            config = getattr(
                self._interface,
                'interface_%s_description' % int_type
            )(**desc_args)
        return callback(config)