writing a service call in the service layer

app-utility.service.ts

login(user_credentials: any){
    let credentials = {...user_credentials};
    return this.serviceWrapper(
      'POST',
      this.getAPI('login'),
      (response: any) => {
        if(response.responseCode == 200){
          return {'data': response};
        }else{
          return {'error': response};
        }
      },
      {
        body: credentials
      }
    );
  }