You can also make your print_h_byref code a little easier to read by using the example from the documentation of the "each" function:

sub print_h_byref {
   my $href = shift;
   
   while (my ($key, $value) = each %$href) {
       print "  Key: $key,\t Value: $value\n";
   }
}
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Your print_h function makes a local copy of the hash. You should be aware that this may become an issue for large hashes, or if it is called a large number of times.