Adds the specified element to this set and all of its supersets.
Adds the specified element to this set and all of its supersets.
void add(IElement element);
Adds the specified label to this set and all of its supersets. Does not apply to subsets of Integers.
void add(String label);
Adds the specified label to this set and all of its supersets. Applies to subsets of Integers.
void add(int label);