The MuxAsyncIterator class multiplexes multiple async iterators into a single stream. It currently makes an assumption:

• The final result (the value returned and not yielded from the iterator) does not matter; if there is any, it is discarded.

Creates a Promise with the reject and resolve functions placed as methods on the promise object itself. It allows you to do:

pooledMap transforms values from an (async) iterable into another async iterable. The transforms are done concurrently, with a max concurrency defined by the poolLimit.