q.pl6

my token text
{
    \N+

    # optional additional lines of offset text
    [
        $$

        \n

        ^^

        $<leading-whitespace> = \h* {}
        :my UInt:D $leading-whitespace = $/<leading-whitespace>.chars;
        { say '[DEBUG] $leading-whitespace: ', $leading-whitespace.perl }

        \N+
    ]*
}

my Str $text = q:to/EOF/.trim-trailing;
  line 1
  line 2
  line 3
  line 4
EOF

say so $text ~~ &text;