在接口内定义匿名回调的语法

import {TestCallback} from ‘./TestCallback’; 
 
@Entry 
@Component 
struct Index { 
  @State message: string = ‘Hello World’; 
 
  aboutToAppear(): void { 
    this.testCallback((data) =>{ 
      console.log(data = ${data}) 
    }); 
  } 
 
  testCallback(callback: TestCallback<number>) { 
    callback(12); 
  } 
 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
      } 
      .width(‘100%’) 
    } 
    .height(‘100%’) 
  } 
}