def master_ref(self):
        """
        Filters the current DataFrame references to only contain those rows whose reference is master.

        >>> master_df = repos_df.master_ref

        :rtype: ReferencesDataFrame
        """
        return ReferencesDataFrame(self._engine_dataframe.getReferences().getHEAD(),
                                   self._session, self._implicits)
Filters the current DataFrame references to only contain those rows whose reference is master.

        >>> master_df = repos_df.master_ref

        :rtype: ReferencesDataFrame