docs: def imap_unordered(self, func, iterable, chunksize=1):
          """The same as imap() except that the ordering of the results
          from the returned iterator should be considered
          arbitrary. (Only when there is only one worker process is the
          order guaranteed to be "correct".)"""
          collector = UnorderedResultCollector()
          self._create_sequences(func, iterable, chunksize, collector)
          return iter(collector)