export class Counter {
	private readonly count = new Map<string, number>();

	add(key: string, amount: number): void {
		this.count.set(key, this.get(key) + amount);
	}

	get(key: string): number {
		return this.count.get(key) ?? 0;
	}

	update(other: Counter): void {
		for (const [key, amount] of other.entries())
			this.add(key, amount);
	}

	entries(): IterableIterator<[string, number]> {
		return this.count.entries();
	}
}