code: def weighted_choice(lst):
      
      n = random.uniform(0, 1)
      for item, weight in lst:
          if n < weight:
              break
          n = n - weight
      return item
docs: Makes weighted choices.  Accepts a list of tuples with the item and
      probability as a pair like:
      >>> x = [('one', 0.25), ('two', 0.25), ('three', 0.5)]
      >>> y=windex(x)