Before:
$VAR1 = {
          'one' => 1,
          'two' => 2
        };

set_element:
$VAR1 = {
          'baz' => 4,
          'one' => 1,
          'two' => 2
        };

Attempt to assign new hashref:
$VAR1 = {
          'baz' => 4,
          'one' => 1,
          'two' => 2
        };