/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
export function once(fn) {
    var _this = this;
    var didCall = false;
    var result;
    return function () {
        if (didCall) {
            return result;
        }
        didCall = true;
        result = fn.apply(_this, arguments);
        return result;
    };
}