Importing rxjs operators style

[jzahka]

Thanks for putting together this repo!

I have a question on style of importing rxjs operators. In Step 9 import './rxjs.operators'; is included in app.module.ts and not needed anywhere else in the project. In Step 10, import './rxjs.operators'; is removed from app.module.ts and included in each file that needs it.

Why not keep the import in app.module.ts as opposed to adding it in each file?