odd const

void Node::validateHierarchy( bool forceUpdate ) const //   here are problem
{
	if ( (m_flag & NODE_WORLDDIRTY) || forceUpdate )
	{
		// compute model->world transform
		Node* parent = this->parent();
		if ( parent )
			m_worldTransform = parent->m_worldTransform * m_localTransform;
		else
			m_worldTransform = m_localTransform;
		
		m_flag &= ~NODE_WORLDDIRTY;
		forceUpdate = true;
	}

	std::vector<Node*>::iterator it, begin, end;
	begin = m_child.begin();//   here are problem
	end = m_child.end();

	for ( it = begin;it != end; it++)
		it.validateHierarchy( forceUpdate );
}