Variable reducers`Const`

reducers: {
    agentAccounts: (state?: Account[], action: ReducerActions) => Account[];
    instance: (
        state?: null | Instance,
        action: ReducerActions,
    ) => null | Instance;
    notificationProblems: (
        state?: NotificationProblemOption[],
        action: ReducerActions,
    ) => NotificationProblemOption[];
} = ...