各位好想請問一下angular的教程中，會用到primise的用法，但他可能搭配了typescript，等方式在寫，我弄了一下還是不是很懂下方是案例：

getHero(id: number): Promise<Hero> {
    return this.getHeroes()
               .then(heroes => heroes.find(hero => hero.id === id));
  }

他跟一般定義resolve與reject去return用法好像不同，
不太理解 Promise<> ，這個的用法<>中的 Hero 是指 then 中retuen會傳給Hero?Hero必須是某一個typescript定義的結構？
對於他到的回傳方式跟彼此對應的關係不是很能理解解..

完整案例

import { Hero } from './hero';
import { HEROES } from './mock-heroes';
import { Injectable } from '@angular/core';

@Injectable()
export class HeroService {
  getHeroes(): Promise<Hero[]> {
    return Promise.resolve(HEROES);
  }

  getHeroesSlowly(): Promise<Hero[]> {
    return new Promise(resolve => {
      // Simulate server latency with 2 second delay
      setTimeout(() => resolve(this.getHeroes()), 2000);
    });
  }

  getHero(id: number): Promise<Hero> {
    return this.getHeroes()
               .then(heroes => heroes.find(hero => hero.id === id));
  }
}

./hero

export class Hero {
  id: number;
  name: string;
}

./mock-heroes

import { Hero } from './hero';

export const HEROES: Hero[] = [
  { id: 11, name: 'Mr. Nice' },
  { id: 12, name: 'Narco' },
  { id: 13, name: 'Bombasto' },
  { id: 14, name: 'Celeritas' },
  { id: 15, name: 'Magneta' },
  { id: 16, name: 'RubberMan' },
  { id: 17, name: 'Dynama' },
  { id: 18, name: 'Dr IQ' },
  { id: 19, name: 'Magma' },
  { id: 20, name: 'Tornado' }
];

https://angular.io/tutorial