src/vs/platform/checksum/node/checksumService.ts/ChecksumService/checksum
class ChecksumService:	async checksum(resource: URI): Promise<string> {
		const stream = (await this.fileService.readFileStream(resource)).value;
		return new Promise<string>((resolve, reject) => {
			const hash = createHash('md5');

			listenStream(stream, {
				onData: data => hash.update(data.buffer),
				onError: error => reject(error),
				onEnd: () => resolve(hash.digest('base64').replace(/=+$/, ''))
			});
		});
	}