use strict;
use warnings;

sub incStart {
    my ($start,$end,$mod) = @_; 
    my @result;
    for ( my $x = $start ; $x < $end ; $x++ ) {
        if ( ( $x % $mod ) == 0 ) {
           push @result,$x;  # append $x to result list
        }
    }
    return @result;  # <- return AFTER completing the loop
}

print "test ";
foreach my $result (incStart(0,10,3)) {
   print "$result\n";
}