回调函数怎么写比较好

interface IEngineCallback { 
  onBegin(id: string) : void; 
  onResult(id: string, text: string): void; 
  onEnd (id: string): void; 
}

interface IEngineCallback { 
  onBegin: (id: string) => void; 
  onResult: (id: string, text: string) => void; 
  onEnd: (id: string) => void; 
} 
 
let a: IEngineCallback = { 
  onBegin: (id: string) => {}, 
  onResult: (id: string,text:string) => {}, 
  onEnd: (id: string) => {} 
}