abstract public function sanitize($string);

  public function &prep(&$data, $op = self::PREP_HOP) {
    if($op & self::PREP_DEMOLISH) 
	  $data = array($data); 
    foreach($data as &$v) {        
	  if(is_array($v)) {
	    if($op & self::PREP_COLLAPSE) 
		  $v = array_map('_collapse', $v);
		$v = (($op & self::PREP_JOIN) 
		    ? join(',', self::prep($v)) 
			  : self::prep($v)
	    );
	  }
      else 
	    $v = self::sanitize($v);
    }  
    return $data;
  }