if Segment.find(:first, :conditions => [ "visible = 1 and (node_a = ? or node_b = ?)", node.id, node.id])
render :nothing => true, :status => HTTP_PRECONDITION_FAILED
else
if Segment.find(:first, :conditions => [ "visible = 1 and (node_a = ? or node_b = ?)", node.id, node.id])
render :nothing => true, :status => HTTP_PRECONDITION_FAILED
else