Nested variable loops

<?php

$visitors_a = ['a', 'b', 'c'];
$visitors_b = ['A', 'B', 'C'];
$visitors_c = [1,2,3,4];
$visitors_d = ['!', '@', '#', '$'];

function loophandle($vector, $data = []) {
    $item = array_shift($vector);
    foreach($item as $val) {
        if (sizeof($vector))
            loophandle($vector, array_merge($data, [$val]));
        else
            echo implode(",", array_merge($data, [$val]))."\n";
    }
}

loophandle([$visitors_a, $visitors_b, $visitors_c, $visitors_d]);

/* expected result:
a,A,1,!
a,A,1,@
a,A,1,#
a,A,1,$
a,A,2,!
a,A,2,@
a,A,2,#
a,A,2,$
a,A,3,!
a,A,3,@
a,A,3,#
a,A,3,$
a,A,4,!
a,A,4,@
a,A,4,#
a,A,4,$
a,B,1,!
a,B,1,@
a,B,1,#
a,B,1,$
a,B,2,!
a,B,2,@
a,B,2,#
a,B,2,$
a,B,3,!
a,B,3,@
a,B,3,#
a,B,3,$
a,B,4,!
a,B,4,@
a,B,4,#
a,B,4,$
a,C,1,!
a,C,1,@
a,C,1,#
a,C,1,$
a,C,2,!
a,C,2,@
a,C,2,#
a,C,2,$
a,C,3,!
a,C,3,@
a,C,3,#
a,C,3,$
a,C,4,!
a,C,4,@
a,C,4,#
a,C,4,$
b,A,1,!
b,A,1,@
b,A,1,#
b,A,1,$
b,A,2,!
b,A,2,@
b,A,2,#
b,A,2,$
b,A,3,!
b,A,3,@
b,A,3,#
b,A,3,$
b,A,4,!
b,A,4,@
b,A,4,#
b,A,4,$
b,B,1,!
b,B,1,@
b,B,1,#
b,B,1,$
b,B,2,!
b,B,2,@
b,B,2,#
b,B,2,$
b,B,3,!
b,B,3,@
b,B,3,#
b,B,3,$
b,B,4,!
b,B,4,@
b,B,4,#
b,B,4,$
b,C,1,!
b,C,1,@
b,C,1,#
b,C,1,$
b,C,2,!
b,C,2,@
b,C,2,#
b,C,2,$
b,C,3,!
b,C,3,@
b,C,3,#
b,C,3,$
b,C,4,!
b,C,4,@
b,C,4,#
b,C,4,$
c,A,1,!
c,A,1,@
c,A,1,#
c,A,1,$
c,A,2,!
c,A,2,@
c,A,2,#
c,A,2,$
c,A,3,!
c,A,3,@
c,A,3,#
c,A,3,$
c,A,4,!
c,A,4,@
c,A,4,#
c,A,4,$
c,B,1,!
c,B,1,@
c,B,1,#
c,B,1,$
c,B,2,!
c,B,2,@
c,B,2,#
c,B,2,$
c,B,3,!
c,B,3,@
c,B,3,#
c,B,3,$
c,B,4,!
c,B,4,@
c,B,4,#
c,B,4,$
c,C,1,!
c,C,1,@
c,C,1,#
c,C,1,$
c,C,2,!
c,C,2,@
c,C,2,#
c,C,2,$
c,C,3,!
c,C,3,@
c,C,3,#
c,C,3,$
c,C,4,!
c,C,4,@
c,C,4,#
c,C,4,$

*/