Demo:  of

The of operator creates an observable data stream out of a comma separated list of data.

//Hint: On the timescale above the output will look overlapped
let input = of(5, 15, 25, 40, 20);

//let's add 1sec delay after each data to remove the overlap
let process = concatMap(v => of(v).pipe(delay(1000)));

let output = input.pipe(process).subscribe(v=>console.log(v))