@pexdoc.pcontracts.contract(dfilter="<STR_LIT>")<EOL><INDENT>def add_dfilter(self, dfilter):<DEDENT>
self._add_dfilter_int(dfilter)<EOL>
r"""
        Add more row(s) or column(s) to the existing data filter.

        Duplicate filter values are eliminated

        :param dfilter: Row and/or column filter
        :type  dfilter: :ref:`CsvDataFilter`

        .. [[[cog cog.out(exobj.get_sphinx_autodoc()) ]]]
        .. Auto-generated exceptions documentation for
        .. putil.pcsv.csv_file.CsvFile.add_dfilter

        :raises:
         * RuntimeError (Argument \`dfilter\` is not valid)

         * RuntimeError (Invalid column specification)

         * ValueError (Column *[column_identifier]* not found)

        .. [[[end]]]