code: def convert_key_to_index(keys, key):
      '''
      convert ``key`` of various types to int or list of int
  
      return index, single
      '''
      index = _key_to_index(keys, key)
      single = isinstance(index, int)
      return index, singlf convert_key_to_index(keys, key):
      '''
      convert ``key`` of various types to int or list of int
  
      return index, single
      '''
      index = _key_to_index(keys, key)
      single = isinstance(index, int)
      return index, single
docs: convert ``key`` of various types to int or list of int
  
      return index, single