-import { asyncScheduler, Observable } from 'rxjs'
-import { bufferTime, distinctUntilChanged, filter, map, observeOn, share, switchMap } from 'rxjs/operators'
-import { NgZone } from '@angular/core'
-import { enterZone, leaveZone } from './zone'
+import { Observable } from 'rxjs'
+import { bufferTime, distinctUntilChanged, filter, map, share, switchMap } from 'rxjs/operators'