code: public function database($db)
      {
          $connection = $this->connection;
          $connection->db = $db;
  
          $this->constructConnections = $connection;
          $connection = class_exists("Clusterpoint\Connection") ? new Connection($this->constructConnections) : new StandartConnection($this->constructConnections);
          return new Service($connection);
      }
docs: Creates Service instance that extends Query Builder.
  
  @param  string  $db
  @return \Clusterpoint\Instance\Service