Sends elements downstream with speed limited to elements/per. In other words, this stage set the maximum rate for emitting messages. This combinator works for streams where all elements have the same cost or length. Throttle implements the token bucket model. There is a bucket with a given token capacity (burst size or maximumBurst). Tokens drops into the bucket at a given rate and can be "spared" for later use up to bucket capacity to allow some burstiness. Whenever stream wants to send an element, it takes as many tokens from the bucket as number of elements. If there isn't any, throttle waits until the bucket accumulates enough tokens. Parameter mode manages behaviour when upstream is faster than throttle rate:

- Shaping makes pauses before emitting messages to meet throttle rate

- Enforcing fails with exception when upstream is faster than throttle rate. Enforcing cannot emit elements that cost more than the maximumBurst

Emits when upstream emits an element and configured time per each element elapsed

Backpressures when downstream backpressures

Completes when upstream completes

Cancels when downstream cancels

public static Source<TOut, TMat> Throttle<TOut, TMat>(
	this Source<TOut, TMat> flow,
	int elements,
	TimeSpan per,
	int maximumBurst,
	ThrottleMode mode
)

[<ExtensionAttribute>]
static member Throttle : 
        flow : Source<'TOut, 'TMat> * 
        elements : int * 
        per : TimeSpan * 
        maximumBurst : int * 
        mode : ThrottleMode -> Source<'TOut, 'TMat>