whole_func_string: function snakeCase(str, sep = '_') {
      return words(str).reduce(
          (result, word, idx) => result + (idx ? sep : '') + lowerCase(word), ''
      );
  }
func_code_string: function snakeCase(str, sep = '_') {
      return words(str).reduce(
          (result, word, idx) => result + (idx ? sep : '') + lowerCase(word), ''
      );
  }
func_documentation_string: ****************************************
  下划线
  ****************************************