function iteratorFromConcatenated(baseIterators, baseErrorHandler) {
	  return new ChainedIterator(baseIterators, baseErrorHandler);
	}
Create a `LazyIterator` by concatenating underlying streams, which are
themselves provided as a stream.

This can also be thought of as a "stream flatten" operation.

@param baseIterators A stream of streams to be concatenated.
@param baseErrorHandler An optional function that can intercept `Error`s
  raised during a `next()` call on the base stream.  This function can decide
  whether the error should be propagated, whether the error should be
  ignored, or whether the base stream should be terminated.