text: (function() {
      'use strict';
  
      angular.module('WhatsApp.services')
          .service('AuthSvr', AuthSvr);
  
      AuthSvr.$inject = ['$firebaseAuth', 'UsersSrv'];
  
      function AuthSvr($firebaseAuth, UsersSrv) {
          const auth = $firebaseAuth();
  
          this.signUp = (firstName, lastName, email, password) => {
              return auth.$createUserWithEmailAndPassword(email, password).then(user => {
                  return UsersSrv.add(user.uid, firstName, lastName, email);
              });
          };
  
          this.signIn = (email, password) => auth.$signInWithEmailAndPassword(email, password);
  
          this.user = () => ({ uid: id, email: email } = auth.$getAuth()); // ES6 destructuring
  
          this.signOut = () => auth.$signOut();
  
          this.isConnected = () => auth.$requireAuth();
      };
  })();