write out a meta data array to the key as a fixed-format Series

        Parameters
        ----------
        key : string
        values : ndarray

def write_metadata(self, key, values):
        """
        write out a meta data array to the key as a fixed-format Series

        Parameters
        ----------
        key : string
        values : ndarray

        """
        values = Series(values)
        self.parent.put(self._get_metadata_path(key), values, format='table',
                        encoding=self.encoding, errors=self.errors,
                        nan_rep=self.nan_rep)