my @arr = (0,0,1, 3,2,0, 1,1,1);
my @output;
for @arr -> $a, $b, $c {
    @output.push: $a + $b + $c;
}

say @output.perl;
# output: [1, 5, 3]

##</code><code>##

my @arr = (0,0,1, 3,2,0, 1,1,1);
my @output = gather {
    for @arr -> $a, $b, $c {
        take $a + $b + $c;
    }
}