docs: def normalize_value(value, snake_case=True):
      """
      :param value:
      :return value:
      """
      if not isinstance(value, six.string_types):
          raise TypeError("the value passed to value must be a string")
  
      if snake_case:
          s1 = first_cap_re.sub(r'\1_\2', value)
          new_value = all_cap_re.sub(r'\1_\2', s1).lower()  # .replace('-', '_')
      else:
          new_value = value.lower()
  
      return new_value