question: public void uncollapse ( Set < Integer > toUncollapse , Set < Integer > collapsedIds ) { Set < Integer > newCollapsed = new HashSet < > ( ) ; for ( Node v = getFirstNode ( ) ; v != null ; v = v . getNext ( ) ) { int vId = ( Integer ) v . getInfo ( ) ; if ( toUncollapse . contains ( vId ) && collapsedIds . contains ( vId ) ) { for ( Edge e = v . getFirstOutEdge ( ) ; e != null ; e = v . getNextOutEdge ( e ) ) { Node w = e . getTarget ( ) ; newCollapsed . add ( ( Integer ) w . getInfo ( ) ) ; } } } collapsedIds . removeAll ( toUncollapse ) ; collapsedIds . addAll ( newCollapsed ) ; }
target:  modify the given set of collapsedIds so that the toUncollapse ids are uncollapsed