src/main/java/io/reactivex/Flowable.java
@CheckReturnValue
    @BackpressureSupport(BackpressureKind.ERROR)
    @SchedulerSupport(SchedulerSupport.COMPUTATION)
    public static Flowable<Long> intervalRange(long start, long count, long initialDelay, long period, TimeUnit unit) {
        return intervalRange(start, count, initialDelay, period, unit, Schedulers.computation());
    }
@CheckReturnValue
    @BackpressureSupport(BackpressureKind.ERROR)
    @SchedulerSupport(SchedulerSupport.COMPUTATION)
    public static Flowable<Long> intervalRange(long start, long count, long initialDelay, long period, TimeUnit unit) {
        return intervalRange(start, count, initialDelay, period, unit, Schedulers.computation());
    }
Signals a range of long values, the first after some initial delay and the rest periodically after.
<p>
The sequence completes immediately after the last value (start + count - 1) has been reached.
<dl>
<dt><b>Backpressure:</b></dt>
<dd>The operator signals a {@code MissingBackpressureException} if the downstream can't keep up.</dd>
<dt><b>Scheduler:</b></dt>
<dd>{@code intervalRange} by default operates on the {@link Schedulers#computation() computation} {@link Scheduler}.</dd>
</dl>
@param start that start value of the range
@param count the number of values to emit in total, if zero, the operator emits an onComplete after the initial delay.
@param initialDelay the initial delay before signaling the first value (the start)
@param period the period between subsequent values
@param unit the unit of measure of the initialDelay and period amounts
@return the new Flowable instance