function D(TokenStream $ts)
{
$cur = $ts->GetCurrentKind();
if ($cur == Kind::digit_0 or $cur == Kind::digit_1 or $cur == Kind::digit_2 or $cur == Kind::digit_3 or $cur == Kind::digit_4 or $cur == Kind::digit_5 or $cur == Kind::digit_6 or $cur == Kind::digit_7 or $cur == Kind::digit_8 or $cur == Kind::digit_9) {
$ts->MoveNext();
return new OutValue($cur, $cur);
} else {
throw new Exception("Input is incorrect.");
}
}