C:\Users\pritesh\textfiles>perl undef.pl
Before: $VAR1 = {};
After: $VAR1 = {
          '1' => undef,
          '3' => undef,
          '54' => undef,
          '2' => undef,
          '4' => undef,
          '45' => undef,
          '55' => undef
        };