my Str $test = q{ULL
RRDDD
LURDL
UUUUD
};
subset DirectionList of List where { .map({$_ ~~ Str and $_ ~~ 'U'|'D'|'L'|'R'|"\n"}) ==> reduce { $^a and $^b} }
say $test.comb ~~ DirectionList;
sub dl(DirectionList $d) is export {
    for $d {
        say $_;
    }
}
dl($test.comb);