private function getRandomUser()
 {
     $payload = new UsersListPayload();
     $response = $this->apiClient->send($payload);
     $users = $response->getUsers();
     $user = $users[array_rand($users)];
     return User::fromSlack($user);
 }
 public function getRandomMessageForUser(User $user)
 {
     return new Message(str_replace('%USERNAME%', '@' . $user->getUsername(), $this->messages[array_rand($this->messages)]));
 }