title: Angular 6 add items into Observable
body: <p>I'm new to Angular 6 and i'm having trouble on how i can add objects into observable in a service.</p>
  
  <p>i have this observable</p>
  
  <pre><code> getContacts(){
    return this.contact = 
    this.http.get('https://jsonplaceholder.typicode.com/users');
   }
  </code></pre>
  
  <p>and i need to add an item into that observable via another function</p>
  
  <pre><code>addContact(item){
   //observable insertion goes here.
  }
  </code></pre>
  
  <p>Here is my full service code</p>
  
  <pre><code>export class ContactService {
  
  contact;
  details;
  
  constructor(private http: HttpClient) {}
  
  getContacts(){
   return this.contact = 
   this.http.get('https://jsonplaceholder.typicode.com/users');
  }
  
  addContact(contactName: string, contactPhone: string){
  
  }
  
  }
  </code></pre>