sub guess()

sub guess (Str $g) returns Bool {
    my $guess = uc $g;
    return 1 if $guess eq any(@guesses);
    return 1 if $guess.chars > 1;
    @guesses.push($guess);
    my $success = 0;
    my $i;
    loop ($i = 0; $i < +@letters; $i++) {
        if (uc(@letters[$i]) eq $guess) {
            @solution[$i] = @letters[$i];
            $success = 1;
        }
    }
    return $success;
}