Marble Diagram

    // textual representation
    0--1--2--3-->// rx.delay(0, 1000)
    --0--1--2--3--| // rx.interval(1000).take(3)

    [a-z0-9]: '0', '1', '2', '3' any alphanumeric character: represents a value being emitted by the producer signaling next()
    '#': error: an error terminating the observable. This is the observable producer signaling error()
    '|': complete: The successful completion of an observable. This is the observable producer signaling complete()
    '-': is a frame
    '-->': is the timeline
    '( )': sync groupings: when multiple events occurred in the same frame synchronously
    '^': subscription point: point out when the observables will be subscribed that concern only Hot observables