offset method

Rank? offset(int delta)

Returns the rank offset by delta.

Returns null if the resulting rank is out of bounds.

Implementation

Rank? offset(int delta) {
  assert(delta >= -7 && delta <= 7);
  final newRank = value + delta;
  if (newRank < 0 || newRank > 7) {
    return null;
  }
  return Rank(newRank);
}