src/vs/platform/files/node/diskFileSystemProvider.ts/DiskFileSystemProvider/normalizePos
class DiskFileSystemProvider:	private normalizePos(fd: number, pos: number): number | null {

		// When calling fs.read/write we try to avoid passing in the "pos" argument and
		// rather prefer to pass in "null" because this avoids an extra seek(pos)
		// call that in some cases can even fail (e.g. when opening a file over FTP -
		// see https://github.com/microsoft/vscode/issues/73884).
		//
		// as such, we compare the passed in position argument with our last known
		// position for the file descriptor and use "null" if they match.
		if (pos === this.mapHandleToPos.get(fd)) {
			return null;
		}

		return pos;
	}