classPersonclassRecordNotFound<StandardError;endincludeGlobalID::Identificationattr_reader:iddefself.find(id)raiseRecordNotFound.new("Cannot find person with ID=404")ifid.to_i==404new(id)enddefinitialize(id)@id=idenddef==(other_person)other_person.is_a?(Person)&&id.to_s==other_person.id.to_sendend