code: def retrieveVals(self):
          
          if self._diskList:
              self._fetchDevAll('disk', self._diskList, 
                                self._info.getDiskStats)
          if self._mdList:
              self._fetchDevAll('md', self._mdList, 
                                self._info.getMDstats)
          if self._partList:
              self._fetchDevAll('part', self._partList, 
                                self._info.getPartitionStats) 
          if self._lvList:
              self._fetchDevAll('lv', self._lvList, 
                                self._info.getLVstats)
          self._fetchDevAll('fs', self._fsList, 
                            self._info.getFilesystemStats)
docs: Retrieve values for graphs.