docs: def reduce_value(value, default=EMPTY_STR):
      """
      :return: a single value from lists, tuples or sets with one item;
      otherwise, the value itself if not empty or the default if it is.
      """
  
      if hasattr(value, '__len__'):
          vlen = len(value)
  
          if vlen == 0:
              return default
          elif vlen == 1:
              if isinstance(value, set):
                  return value.pop()
              elif isinstance(value, _reduce_types):
                  return value[0]
  
      return default if value is None else value