original_string: public static function isLuhn($val = null)
      {
          if (is_null($val)) {
              return null;
          }
          $_num = substr($val, 0, strlen($val)-1);
          return (bool) (intval($val) == intval($_num.self::getLuhnKey($_num)));
      }
code: public static function isLuhn($val = null)
      {
          if (is_null($val)) {
              return null;
          }
          $_num = substr($val, 0, strlen($val)-1);
          return (bool) (intval($val) == intval($_num.self::getLuhnKey($_num)));
      }
code_tokens: public static function isLuhn ( $ val = null ) { if ( is_null ( $ val ) ) { return null ; } $ _num = substr ( $ val , 0 , strlen ( $ val ) - 1 ) ; return ( bool ) ( intval ( $ val ) == intval ( $ _num . self :: getLuhnKey ( $ _num ) ) ) ; }
docstring: Check that the last number in a suite is its Luhn key
  
  @param   int     $val    The number to check INCLUDING Luhn's key at last
  @return  bool
docstring_tokens: Check that the last number in a suite is its Luhn key