function blueFeetMixin<T extends DuckConstructor>(Duck: T) {
  return class blueFeetDuck extends Duck {
    hasBlueFeet(): boolean {
      return true
    }

    getFeatherColours(): string {
      return 'blue'
    }
  };
}
	function blueFeetMixin<T extends DuckConstructor>(Duck: T) {
	return class blueFeetDuck extends Duck {
	hasBlueFeet(): boolean {
	return true
	}

	getFeatherColours(): string {
	return 'blue'
	}
	};
	}