whole_func_string: function map(mapper) {
      return function* (iterable) {
          let index = 0;
          for (const value of iterable) {
              yield mapper(value, index);
              index = index + 1;
          }
      };
  }
func_code_string: function map(mapper) {
      return function* (iterable) {
          let index = 0;
          for (const value of iterable) {
              yield mapper(value, index);
              index = index + 1;
          }
      };
  }
func_documentation_string: Yield a new iterable sequence that applies the mapper to every item in the original