extensions/references-view/src/calls/index.ts/RichCallsDirection/constructor
class RichCallsDirection:	constructor(
		private _mem: vscode.Memento,
		private _value: CallsDirection = CallsDirection.Outgoing,
	) {
		const raw = _mem.get<number>(RichCallsDirection._key);
		if (typeof raw === 'number' && raw >= 0 && raw <= 1) {
			this.value = raw;
		} else {
			this.value = _value;
		}
	}