calculateLeave(username:string, password:string): Observable<number> {
    let params = new URLSearchParams();
    params.append("username", username);
    params.append("password", password);
    return this.http.get("api/calculateleave", {params: params}).subscribe(res => res.json() as number);//this.http.get(this.apiPostUrl, {params: params}).toPromise().then(res => res.json() as Account)
  }