code: def get_previous_cursor_time(self, project_name, logstore_name, shard_id, cursor, normalize=True):
          
  
          try:
              pre_cursor_int = self._get_cursor_as_int(cursor) - 1
              pre_cursor = e64(str(pre_cursor_int)).strip()
          except Exception:
              raise LogException("InvalidCursor", "Cursor {0} is invalid".format(cursor))
  
          try:
              return self.get_cursor_time(project_name, logstore_name, shard_id, pre_cursor)
          except LogException as ex:
              if normalize and ex.get_error_code() == "InvalidCursor":
                  ret = self.get_begin_cursor(project_name, logstore_name, shard_id)
                  begin_cursor_int = self._get_cursor_as_int(ret.get_cursor())
  
                  if pre_cursor_int < begin_cursor_int:
                      return self.get_cursor_time(project_name, logstore_name, shard_id, e64(str(begin_cursor_int)))
  
                  ret = self.get_end_cursor(project_name, logstore_name, shard_id)
                  end_cursor_int = self._get_cursor_as_int(ret.get_cursor())
  
                  if pre_cursor_int > end_cursor_int:
                      return self.get_cursor_time(project_name, logstore_name, shard_id, e64(str(end_cursor_int)))
  
              raise ex
docs: Get previous cursor time from log service.
          Note: normalize = true: if the cursor is out of range, it will be nornalized to nearest cursor
          Unsuccessful opertaion will cause an LogException.
  
          :type project_name: string
          :param project_name: the Project name
  
          :type logstore_name: string
          :param logstore_name: the logstore name
  
          :type shard_id: int
          :param shard_id: the shard id
  
          :type cursor: string
          :param cursor: the cursor to get its service receive time
  
          :type normalize: bool
          :param normalize: fix the cursor or not if it's out of scope
  
          :return: GetCursorTimeResponse
  
          :raise: LogException