public static function getMutation(array &$tokens, $index)
    {
        $num = (integer) $tokens[$index][1];
        if ($num == 0) {
            $replace = 1;
        } elseif ($num == 1) {
            $replace = 0;
        } else {
            $replace = $num + 1;
        }
        $tokens[$index] = [
            T_LNUMBER,
            (string) $replace
        ];
    }
public static function getMutation(array &$tokens, $index)
    {
        $num = (integer) $tokens[$index][1];
        if ($num == 0) {
            $replace = 1;
        } elseif ($num == 1) {
            $replace = 0;
        } else {
            $replace = $num + 1;
        }
        $tokens[$index] = [
            T_LNUMBER,
            (string) $replace
        ];
    }
public static function getMutation ( array & $ tokens , $ index ) { $ num = ( integer ) $ tokens [ $ index ] [ 1 ] ; if ( $ num == 0 ) { $ replace = 1 ; } elseif ( $ num == 1 ) { $ replace = 0 ; } else { $ replace = $ num + 1 ; } $ tokens [ $ index ] = [ T_LNUMBER , ( string ) $ replace ] ; }
Replace 1 with 0, 0 with 1, or increment.

@param array $tokens
@param int $index
@return array
Replace 1 with 0 0 with 1 or increment .