use v5.10.0;
use warnings;
use strict;

package Animal;

sub new {
    my $class = $_[0];
    my $self = {text => "I am an abstract animal.\n"};
    return bless($self, $class);
}
sub speak {
    my $self = shift;
    print $self->{"text"}
}

package Duck;
our @ISA = qw(Animal); # qw(Animal) je ekvavilentno ("Animal")

sub new {
    return bless({text => "I am a a duck.\n"}, shift);
}