def charm_icon_url(self, charm_id, channel=None):
        '''Generate the path to the icon for charms.

        @param charm_id The ID of the charm.
        @param channel Optional channel name.
        @return The url to the icon.
        '''
        url = '{}/{}/icon.svg'.format(self.url, _get_path(charm_id))
        return _add_channel(url, channel)
Generate the path to the icon for charms.

        @param charm_id The ID of the charm.
        @param channel Optional channel name.
        @return The url to the icon.