sub foo{
 
 my @this_array;
 my %this_hash;

 foreach....{

    push(@this_array, $something);
    $this_hash{$key} = \@this_array;
    
    #reset this_array for some other operation    
    @this_array=();

    $key = $next_key;
    $something = $some_other_thing;
 }

return(\%this_hash);
}