title: Format of Angular 5 functions
body: <p>I'm looking at this code which represents a class in <code>Angular 5</code>:</p>
  
  <pre><code>export class HeroService {
  
    constructor() { }
  
    getHeroes(): Hero[] {
      return HEROES;
    }
  
  }
  </code></pre>
  
  <p>My question is about the method <code>getHeroes()</code>. What does the <code>: Hero[]</code> portion of the function mean? </p>