code: protected function checkParams($params,$operator)
    {
      if (!is_array($params)) {
      	throw new Exception('Web2All_Table_MultiValueOperator: first param must be an array');
      }
      if ($operator=='IN') {
      	if (count($params)<1) {
      		throw new Exception('Web2All_Table_MultiValueOperator: IN operator requires at least one param');
      	}
      } elseif ($operator=='BETWEEN') {
      	if (count($params)!=2) {
      		throw new Exception('Web2All_Table_MultiValueOperator: BETWEEN operator requires exactly two params');
      	}
      }else{
        throw new Exception('Web2All_Table_MultiValueOperator: unsupported operator "'.$operator.'"');
      }
    }
docs: Checks if params are correct and throws exception if not
  
  @param array $params
  @param string $operator