NB:

sub new {
    my $class = shift;

    my $self = {};

    bless $self, $class;

    return $self;
}
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This allows for children classes to call you as a parent and have the inheritance work. You should NEVER hardcode anything. If you have to do something like bless {}, 'First';, at least do something like bless {}, __PACKAGE__;. That way, if you change the package name, you won't forget to change the name of the package you're blessing this thingy into.

The reason to declare $self first is to allow for you to populate it. :-)

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.