Method FromJust

nan.h:255–260

  }

  inline T FromJust() const {
#if defined(V8_ENABLE_CHECKS)
    assert(IsJust() && "FromJust is Nothing");
#endif  // V8_ENABLE_CHECKS
    return value_;
  }

  inline T FromMaybe(const T& default_value) const {
    return has_value_ ? value_ : default_value;