docs: def __readData(self, targetPath, start, end):
          ''' read data '''
          ret = []
          if not path.exists(targetPath):
              LOG.error("Target file doesn't exist: %s" % path.abspath(targetPath) )
              return ret
  
          with ExcelLib(fileName = targetPath, mode = ExcelLib.READ_MODE) as excel:
              low, high = self.__findRange(excel, start, end)
  
              for index in range(low, high + 1):
                  ret.append(excel.readRow(index))
  
          return ret