docs: def sort_values(self, by, axis=0, ascending=True, inplace=False,
                      kind='quicksort', na_position='last'):
          """Sort by the values along either axis
  
          Wrapper around the :meth:`pandas.DataFrame.sort_values` method.
          """
          if inplace:
              self._frame.sort_values(
                  by, axis=axis, ascending=ascending,
                  inplace=inplace, kind=kind, na_position=na_position)
          else:
              new = self.__class__(self._frame.sort_values(
                  by, axis=axis, ascending=ascending, inplace=inplace,
                  kind=kind, na_position=na_position))
              new.metadata = self.metadata.copy()
              new._metadata = copy.deepcopy(self._metadata)
              return new