message: Update value state in operators(++,+=) for the class Integer.
diff: @@ -185,12 +185,14 @@ Integer<T, minval, maxval>& Integer<T, minval, maxval>::operator=(
  template <typename T, T minval, T maxval>
  Integer<T, minval, maxval>& Integer<T, minval, maxval>::operator++() {
  ++value_;
  + value_state_ = range_.Includes(value_) ? kValid : kInvalid;
  return *this;
  }
  template <typename T, T minval, T maxval>
  Integer<T, minval, maxval>& Integer<T, minval, maxval>::operator+=(int value) {
  value_ += value;
  + value_state_ = range_.Includes(value_) ? kValid : kInvalid;
  return *this;
  }
  