More involved Moose example from Stevan Little

Tree.pm.html

• new has features
• predicate => 'predicate name' - Creates a method that returns a boolean value that checks to see if the attribute is set
• handles => ARRAY HASH REGEXP | CODE - automated delegation
• Tree->add_sibling() is really Tree->parent()->add_child()
• meta
• Access to your classes meta object for introspection
• no moose;
• remove all moose exported sub from the current namespace.