if (null != m_obj && m_obj instanceof NodeSetDTM)
if (m_iter instanceof NodeSetDTM)
  public int getLength()  {  	if(hasCache())  	{        // If this NodeSequence wraps a mutable nodeset, then        // m_last will not reflect the size of the nodeset if        // it has been mutated...        if (null != m_obj && m_obj instanceof NodeSetDTM)        {            return ((NodeSetDTM)m_obj).getLength();        }    	  	if(-1 == m_last)	  	{	  		int pos = m_next;	  		runTo(-1);	  		m_next = pos;	  	}	    return m_last;  	}  	else  	{  		return (-1 == m_last) ? (m_last = m_iter.getLength()) : m_last;  	}  }