code: def QA_util_get_real_date(date, trade_list=trade_date_sse, towards=-1):
      
      date = str(date)[0:10]
      if towards == 1:
          while date not in trade_list:
              date = str(
                  datetime.datetime.strptime(str(date)[0:10],
                                             '%Y-%m-%d') +
                  datetime.timedelta(days=1)
              )[0:10]
          else:
              return str(date)[0:10]
      elif towards == -1:
          while date not in trade_list:
              date = str(
                  datetime.datetime.strptime(str(date)[0:10],
                                             '%Y-%m-%d') -
                  datetime.timedelta(days=1)
              )[0:10]
          else:
              return str(date)[0:10]
docs: 获取真实的交易日期,其中,第三个参数towards是表示向前/向后推
      towards=1 日期向后迭代
      towards=-1 日期向前迭代
      @ yutiansut