my $product = iter_prod( $abcees, $xyzees );

while (defined (my $vals = $product->())) {
    my @vars = @$vals;
    print "Got vars: @vars\n";
    # do real work here
}
# Got vars: a x
# Got vars: a y
# Got vars: a z
# Got vars: b x
# Got vars: b y
# Got vars: b z
# Got vars: c x
# Got vars: c y
# Got vars: c z