code: def values(self, column_major=False):
          
          if column_major:
              return list(map(list, zip(*self._values)))
          return [row[:] for row in self._values]
docs: Return a nested list with the worksheet values.
  
          Args:
              column_major (bool): as list of columns (default list of rows)
          Returns:
              list: list of lists with values