docs: def parse(self, rec):
          """Retrieve row data from files associated with the ISATabRecord.
          """
          final_studies = []
          for study in rec.studies:
              source_data = self._parse_study(study.metadata["Study File Name"],
                                              ["Source Name", "Sample Name", "Comment[ENA_SAMPLE]"])
              if source_data:
                  study.nodes = source_data
                  final_assays = []
                  for assay in study.assays:
                      cur_assay = ISATabAssayRecord(assay)
                      assay_data = self._parse_study(assay["Study Assay File Name"],
                                                     ["Sample Name","Extract Name","Raw Data File","Derived Data File", "Image File", "Acquisition Parameter Data File", "Free Induction Decay Data File"])
                      cur_assay.nodes = assay_data
                      self._get_process_nodes(assay["Study Assay File Name"], cur_assay)
                      final_assays.append(cur_assay)
                  study.assays = final_assays
  
                  #get process nodes
                  self._get_process_nodes(study.metadata["Study File Name"], study)
                  final_studies.append(study)
          rec.studies = final_studies
          return rec