Reference Operations

A reference used like a string is stringized
It now looks like HASH(0x436c2d) or some such.
The 0x436c2d part is the address of the actual data
So eq will compare references also (slower than ==)

        sub unique_objects {
          my (%seen, @result);
          for my $obj (@_) {
            push @result, $obj unless $seen{$obj}++;
          }
          @result;
        }

This is why you should not say

        function("$x");