code: function SessionManager(config, encrypter) {
      /**
       * The configuration object
       *
       * @var Object
       * @protected
       */
      this.__config = config;
  
      /**
       * The registered custom driver creators.
       *
       * @var Object
       * @protected
       */
      this.__customCreators = {};
  
      /**
       * The encrypter instance.
       * An encrypter implements encrypt and decrypt methods.
       *
       * @var Object
       * @protected
       */
      this.__encrypter = encrypter;
  
      /**
       * The session database model instance
       *
       * @var Object
       * @protected
       */
      this.__sessionModel;
  
      /**
       * The memory session handler storage
       * @type {null}
       * @protected
       */
      this.__memorySession = Object.create(null);
  }
docs: Create a session manager instance.
  
  @param {Object} config
  @param {Object} [encrypter]
  
  @constructor