code: def fetchcolumnar(self):
          
          self._wait_to_finish()
          if not self._last_operation.is_columnar:
              raise NotSupportedError("Server does not support columnar "
                                      "fetching")
          batches = []
          while True:
              batch = (self._last_operation.fetch(
                           self.description,
                           self.buffersize,
                           convert_types=self.convert_types))
              if len(batch) == 0:
                  break
              batches.append(batch)
          return batches
docs: Executes a fetchall operation returning a list of CBatches