code: def _do_filter(cnf, args):
      
      if args.query:
          cnf = API.query(cnf, args.query)
      elif args.get:
          cnf = _do_get(cnf, args.get)
      elif args.set:
          (key, val) = args.set.split('=')
          API.set_(cnf, key, anyconfig.parser.parse(val))
  
      return cnf
docs: :param cnf: Mapping object represents configuration data
      :param args: :class:`argparse.Namespace` object
      :return: 'cnf' may be updated