private function validateNip($nip)
{	  
  	  $n = str_replace(array('-', ' '), '', $nip);
  	  
  	  if(strlen($n) !== 10)
  	     return false;
  	  
      $weights = array(6, 5, 7, 2, 3, 4, 5, 6, 7);
      $sum = 0;
      foreach($weights as $i => $w)
      {
        $sum += intval($n{$i}) * $w;
      }
      
      return (($sum % 11) == 10 ? false : true);
}