HarmonyOS ArkTS 有没有extension

class Base { 
     method1() { 
     console.log(‘method1 from Base’); 
     } 
}

class Child extends Base { 
  method1() { 
    console.log(‘method1 from Child’); 
  } 
  method2() { 
    console.log(‘method2 from Child’); 
  } 
}