@pkerschbaum/code-oss-file-service/src/vs/base/common/functional.ts

VS Code ([microsoft/vscode](https://github.com/microsoft/vscode)) includes a rich "`FileService`" and "`DiskFileSystemProvider`" abstraction built on top of Node.js core modules (`fs`, `path`) and Electron's `shell` module. This package allows to use that

/*---------------------------------------------------------------------------------------------
 *  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<T extends Function>(this: unknown, fn: T): T {
	const _this = this;
	let didCall = false;
	let result: unknown;

	return function () {
		if (didCall) {
			return result;
		}

		didCall = true;
		result = fn.apply(_this, arguments);

		return result;
	} as unknown as T;
}