multiclass_inheritance.dart

abstract class Animal implements Run {
  void go() {
    print("I'm Animal");
  }
}

abstract class Bird extends Animal {
  void go() {
    super.go();
    print("I'm Bird");
  }
}

abstract class Run {
  void go();
}

mixin Walker on Run {
  void go() {
    super.go();
    print("I'm walking");
  }
}

mixin Swimmer on Run {
  // This class is intended to be used as a mixin, and should not be
  // extended directly.
  void go() {
    super.go();
    print("I'm swimming");
  }
}

mixin Flyer on Run {
  // This class is intended to be used as a mixin, and should not be
  // extended directly.
  void go() {
    super.go();
    print("I'm flying");
  }
}

class Duck extends Bird with Walker, Swimmer, Flyer {}

void main() {
  Duck().go();
}