addNext(Element element) For each element in this set, adds an edge to the given element.
boolean
contains(ElementSet rhs) Doesn't have to be strict (it's OK for this method to return false
when it's actually true) since this is used just for optimization.
Doesn't have to be strict (it's OK for this method to return false
when it's actually true) since this is used just for optimization.
(Erring on the other side is NG)