<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_filter(self, name, query, color=None, item_order=None):
 """Create a new filter. .. warning:: Requires Todoist premium. :param name: The name of the filter. :param query: The query to search for. :param color: The color of the filter. :param item_order: The filter's order in the filter list. :return: The newly created filter. :rtype: :class:`pytodoist.todoist.Filter` """

        args = {
            'name': name,
            'query': query,
            'color': color,
            'item_order': item_order
        }
        _perform_command(self, 'filter_add', args)
        return self.get_filter(name)