code: def progress(iterator, enum=False, length=None):
      
      progress = ProgressBar()
      length = len(iterator) if length is None else length
      gen = enumerate(iterator)
      while True:
          i, val = next(gen)
          progress((i+1.0)/length * 100)
          if enum:
              yield i, val
          else:
              yield val
docs: A helper utility to display a progress bar when iterating over a
      collection of a fixed length or a generator (with a declared
      length).
  
      If enum=True, then equivalent to enumerate with a progress bar.