docs: def __findRange(self, excelLib, start, end):
          ''' return low and high as excel range '''
          inc = 1
          low = 0
          high = 0
          dates = excelLib.readCol(0, 1)
  
          for index, date in enumerate(dates):
              if int(start) <= int(date):
                  low = index + inc
                  break
  
          if low:
              for index, date in reversed(list(enumerate(dates))):
                  if int(date) <= int(end):
                      high = index + inc
                      break
  
          return low, high