docs: function Context() {
  	/**
  	 * @member {Object}
  	 * @property {Object} client
  	 * @property {Object<Call>} client.map - map from call name and call id
  	 * @property {Array<Call>} client.list
  	 * @property {Object} server
  	 * @property {Object<Call>} server.map - map from call name and call id
  	 * @property {Array<Call>} server.list
  	 * @private
  	 */
  	this._calls = {
  		client: {
  			map: Object.create(null),
  			list: []
  		},
  		server: {
  			map: Object.create(null),
  			list: []
  		}
  	}
  
  	/**
  	 * @member {Object}
  	 * @property {Object} client
  	 * @property {Object<Message>} client.map - map from message name and message id
  	 * @property {Array<Message>} client.list
  	 * @property {Object} server
  	 * @property {Object<Message>} server.map - map from message name and message id
  	 * @property {Array<Message>} server.list
  	 * @private
  	 */
  	this._messages = {
  		client: {
  			map: Object.create(null),
  			list: []
  		},
  		server: {
  			map: Object.create(null),
  			list: []
  		}
  	}
  }