While it's possible to use an Object to configure your streams, using a Function gives you much more flexibility to configure streams. This lesson shows how to use the functions to configure and return multiple streams based on the same source.
I had to use pipe to get this to work.
I imported map import {map} from 'rxjs/operators'
Then used pipe like this interval$.pipe(map(i => i * 2))
Please somebody correct me if this isn't correct.
Only way I could get it working as well Christopher.