code: def strptime(time_str, time_format):
          
          try:
              datetime_obj = datetime.strptime(time_str, time_format)
              return datetime_obj
          except ValueError as ex:
              raise ValueError(ex)
docs: 将 str 转换为 datetime 对象
  
          :param:
              * time_str: (string) 日期字符串
              * time_format: (sting) 日期格式字符串
          :return:
              * datetime_obj: (obj) datetime 对象