code: def append(self, resultFile, resultElem, all_columns=False):
          
          self._xml_results += [(result, resultFile) for result in _get_run_tags_from_xml(resultElem)]
          for attrib, values in RunSetResult._extract_attributes_from_result(resultFile, resultElem).items():
              self.attributes[attrib].extend(values)
  
          if not self.columns:
              self.columns = RunSetResult._extract_existing_columns_from_result(resultFile, resultElem, all_columns)
docs: Append the result for one run. Needs to be called before collect_data().