code: def parse_schedule_str(schedule_str: str) -> List[Tuple[float, int]]:
          
          schedule = list()
          for step in schedule_str.split(","):
              rate, num_updates = step.split(":")
              schedule.append((float(rate), int(num_updates)))
          return schedule
docs: Parse learning schedule string.
  
          :param schedule_str: String in form rate1:num_updates1[,rate2:num_updates2,...]
          :return: List of tuples (learning_rate, num_updates).