add method
Implementation
void add(Entity entity) {
assert(_nextIndex < capacity, 'Too many entities in existence.');
var newIndex = _nextIndex;
entityToIndexList[entity] = newIndex;
indexToEntityList[newIndex] = entity;
_nextIndex++;
}
void add(Entity entity) {
assert(_nextIndex < capacity, 'Too many entities in existence.');
var newIndex = _nextIndex;
entityToIndexList[entity] = newIndex;
indexToEntityList[newIndex] = entity;
_nextIndex++;
}