code: def stream_tap(callables, stream):
      
      for item in stream:
          for caller in callables:
              caller(item)
          yield item
docs: Calls each callable with each item in the stream.
      Use with Buckets. Make a Bucket with a callable
      and then pass a tuple of those buckets
      in as the callables. After iterating over
      this generator, get contents from each Spigot.
  
      :param callables: collection of callable.
      :param stream: Iterator if values.