code: def ilen(iterable):
      
      # This approach was selected because benchmarks showed it's likely the
      # fastest of the known implementations at the time of writing.
      # See GitHub tracker: #236, #230.
      counter = count()
      deque(zip(iterable, counter), maxlen=0)
      return next(counter)
docs: Return the number of items in *iterable*.
  
          >>> ilen(x for x in range(1000000) if x % 3 == 0)
          333334
  
      This consumes the iterable, so handle with care.