code: public boolean isLast()
      {
          if (_parent == null)
              return true;
          int last = _parent.size() - 1;
          assert(last >= 0);
          return (_parent.getChild(last) == this);
      }
docs: Gets whether or not this is the last node in the set of children
  for the parent node.
  @return if this is the last or not