export default interface FollowKeyRepository { getKeys(): string[]; pushKey(key: string): void; popKey(): void; clearKeys(): void; } const current: { keys: string[]; } = { keys: [], }; export class FollowKeyRepositoryImpl implements FollowKeyRepository { getKeys(): string[] { return current.keys; } pushKey(key: string): void { current.keys.push(key); } popKey(): void { current.keys.pop(); } clearKeys(): void { current.keys = []; } }