Improve redux-immutable type definition

types/redux-immutable/index.d.ts

@@ -7,11 +7,11 @@
 // TypeScript Version: 2.3
 
 declare module 'redux-immutable' {
-  import { Collection, Record as ImmutableRecord } from 'immutable';
+  import { Collection, Record } from 'immutable';
   import { ReducersMapObject, Reducer, Action } from 'redux';
 
   export function combineReducers<S, A extends Action, T>(reducers: ReducersMapObject<S, A>, getDefaultState?: () => Collection.Keyed<T, S>): Reducer<S, A>;
   export function combineReducers<S, A extends Action>(reducers: ReducersMapObject<S, A>, getDefaultState?: () => Collection.Indexed<S>): Reducer<S, A>;
   export function combineReducers<S>(reducers: ReducersMapObject<S, any>, getDefaultState?: () => Collection.Indexed<S>): Reducer<S>;
-  export function combineReducers<S>(reducers: ReducersMapObject<S, any>, getDefaultState?: () => ImmutableRecord<any>): Reducer<S>;
+  export function combineReducers<S, T extends object>(reducers: ReducersMapObject<S, any>, getDefaultState?: Record.Factory<T>): Reducer<S>;
 }