code: public function shouldSendError($type, $message, $file = null, $line = null, $context = null)
      {
          return !array_key_exists($type, self::$warningErrors);
      }
docs: Filters out PHP errors before they get sent
  
  @param int $type
  @param string $message
  @param string $file
  @param int $line
  @param array $context
  @see http://us3.php.net/manual/en/function.set-error-handler.php
  @return bool