Adds the label to the set and all its parent sets.
Adds the specified string label to the set and all its super sets. Does not apply to IElements that are associated with subsets of Integers.
virtual void add(const char* label) = 0;
Adds the specified integer label to the set and all its super sets. Does only apply to IElements associated with subsets of Integers.
virtual void add(int label) = 0;
