vehicle_type = EntityType.new('Vehicle', {
    'maker' => 'String',             # class.name
    'model' => 'String',
    'yearCreated' => 'Time',
    'speed' => 'Fixnum',
    'miles' => 'Float'});


vehicle = Entity.new(vehicle_type, {
    'maker' => 'Toyota',
    'model' => 'Highlander',
    'yearCreated' => DateTime.parse('1-1-2003'),
    'speed' => 120,
    'miles' => 3000});
class << vehicle
  def drive
    "driving"
  end
  def stop
    "stopping"
  end
  def perform_maintenance
    "performing maintenance"
  end
end