code: void printPosSets(RBBINode n) {
             if (n==null) {
                 return;
             }
             RBBINode.printNode(n);
             System.out.print("         Nullable:  " + n.fNullable);
  
             System.out.print("         firstpos:  ");
             printSet(n.fFirstPosSet);
  
             System.out.print("         lastpos:   ");
             printSet(n.fLastPosSet);
  
             System.out.print("         followpos: ");
             printSet(n.fFollowPos);
  
             printPosSets(n.fLeftChild);
             printPosSets(n.fRightChild);
         }
docs: -----------------------------------------------------------------------------