RXJS withLatestFrom

/** 
* Only emit from 1st(source) 2nd(inner) obs after both have emitted (onFirst of each) - don't need to complete 
* Only emit the last value present ( of each )
* if one obs completes, the output is the data from the one running plus the last value from the the one completed
* returns a tuple [data1, data2] of each obs-dataset, similar to forkJoin
*/
1$ = from(http src) -> complete
2$ = from( http src ) -> long running

1$.pipe(withLatestFrom(2$)).subscribe([ dataFrom1, dataFrom2])