* Get an item. * @param {String} key The key of the item to get. * @param {?any} defaultValue The default value to return if item does not exist.

* Check if an item exists. * @param {String} key The key of the item to check. * @returns {boolean}

* Delete an item. * @param {String} key The key of the item to delete.

* Set an item. * @param {String} key * @param {?any} value

* Transmit events to the renderer with optional arguements. * @param {String} eventName Name of event to transmit * @param {Array<any>} args Any a

* @param {BrowserWindow} mainWindow