```
type Event = { name: string; timestamp: number };
/** An append-only log of timestamped events. */
export class EventLog {
  #events: Event[];

  constructor() {
    this.#events = [];
  }

  /** Append one event. */
  record(event: Event): void {
    this.#events.push({ ...(event as Event), timestamp });
  }

  /** Every event at or after the given timestamp, in insertion order. */
  since(timestamp: number): Event[] {
    return this.#events.filter((event) => event.timestamp >= timestamp);
  }
}
```