code: def time_choices():
      
      hours = list(range(0, 24))
      times = []
      for h in hours:
          hour = str(h).zfill(2)
          times.append(hour+':00')
          times.append(hour+':30')
      return list(zip(times, times))
docs: Return digital time choices every half hour from 00:00 to 23:30.