whole_func_string: function defer(func) {
      return new (class {
          constructor(generator) {
              this.generator = generator;
          }
          [Symbol.iterator]() {
              return this.generator()[Symbol.iterator]();
          }
      })(func);
  }
func_code_string: function defer(func) {
      return new (class {
          constructor(generator) {
              this.generator = generator;
          }
          [Symbol.iterator]() {
              return this.generator()[Symbol.iterator]();
          }
      })(func);
  }
func_documentation_string: Wraps an iterable factory inside a class that allows it to be repeatedly iterated without state, same as how Arrays work