app.module.ts

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import { AngularFireAuthModule } from 'angularfire2/auth';
import { AngularFireModule } from 'angularfire2';
import { AngularFireAuth } from 'angularfire2/auth';

import { environment } from '../environments/environment';

@NgModule({
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  imports: [
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    AngularFireModule.initializeApp(environment.firebase),
    AngularFireAuthModule
  ],
  providers: [
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    .,
    AngularFireAuth
  ]
})