/* Authenticate a User */
ClientResponse<LoginResponse, Errors> response = client.Login(
  new LoginRequest(new Guid("00000000-0000-0000-0000-00000000002a"), "bob@example.com", null, "secret"), null);
User user = response.successResponse.user;

/* Retrieve User by Email Address */
ClientResponse<UserResponse, Errors> response = client.RetrieveUserByEmail("bob@example.com");
User user = response.successResponse.user;