code: public boolean canTraverseOutsideSubtree()
    {
  
      if (null != m_left && m_left.canTraverseOutsideSubtree())
        return true;
  
      if (null != m_right && m_right.canTraverseOutsideSubtree())
        return true;
  
      return false;
    }
docs: Tell if this expression or it's subexpressions can traverse outside
  the current subtree.
  
  @return true if traversal outside the context node's subtree can occur.