sprinting a Match, using a postfix 'for' instead of a block 'for' does not behave as expected.

MatchSprint.p6

sub sprint( Match:D $m, $nm='TOP', $indent is copy = 0) {
   sub i { ' ' x ($indent * 2) }
   sub show(Str $s) {  $s.substr(0, 30).perl; }

   my $s = '';
   $s = i() ~ "$m.from() $m.to() $nm  " ~ show( ~$m)  ~ "\n";
   for $m.caps {
        $s ~= sprint $_.value, $_.key, $indent++ if $_.value ~~ Match; # for $m.caps;
   }
   $s;
}