#!/usr/bin/perl

use strict;

Cow->speak;

{ package Animal;
  sub speak {
    my $class = shift;
    print "a $class goes ", $class->sound, "!\n";
  }
}

{ package Cow;
  our @ISA = qw(Animal);
  sub sound { "moooo" }
}

##</code><code>##

Can't locate object method "speak" via package "Cow" 
at ./testOO1.pl line 6.