code: public function create()
      {
          if ($this->getIsNewRecord() == false) {
              throw new \RuntimeException('Calling "' . __CLASS__ . '::' . __METHOD__ . '" on existing user');
          }
  
          $this->confirmed_at = time();
  
          if ($this->password == null) {
              $this->password = Password::generate(8);
          }
  
          $this->trigger(self::USER_CREATE_INIT);
  
          if ($this->save()) {
              $this->trigger(self::USER_CREATE_DONE);
              $this->mailer->sendWelcomeMessage($this);
              \Yii::getLogger()->log('User has been created', Logger::LEVEL_INFO);
              return true;
          }
  
          \Yii::getLogger()->log('An error occurred while creating user account', Logger::LEVEL_ERROR);
  
          return false;
      }
docs: This method is used to create new user account. If password is not set, this method will generate new 8-char
  password. After saving user to database, this method uses mailer component to send credentials
  (username and password) to user via email.
  
  @return bool