What will result and fallback be?

const Maybe = <T>(value: T | null | undefined) => ({
  map: <U>(fn: (val: T) => U) =>
    value != null ? Maybe(fn(value)) : Maybe<U>(null),
  getOrElse: (defaultVal: T) =>
    value != null ? value : defaultVal,
});

const result = Maybe("hello")
  .map(s => s.toUpperCase())
  .map(s => s + "!")
  .getOrElse("default");

const fallback = Maybe<string>(null)
  .map(s => s.toUpperCase())
  .getOrElse("default");