whole_func_string: function filter(predicate) {
      return flatMap(value => predicate(value) ? maybe_1.just(value) : maybe_1.nothing());
  }
func_code_string: function filter(predicate) {
      return flatMap(value => predicate(value) ? maybe_1.just(value) : maybe_1.nothing());
  }
func_documentation_string: Return the current maybe if it has a value that matches the predicate, else return an empty