How to use the dataflows.helpers.rows_processor function in dataflows

def _chain(self, ds=None):
        from ..helpers import datapackage_processor, rows_processor, row_processor, iterable_loader

        for position, link in enumerate(self._preprocess_chain(), start=1):
            if isinstance(link, Flow):
                ds = link._chain(ds)
            elif isinstance(link, DataStreamProcessor):
                ds = link(ds, position=position)
            elif isfunction(link):
                sig = signature(link)
                params = list(sig.parameters)
                if len(params) == 1:
                    if params[0] == 'row':
                        ds = row_processor(link)(ds, position=position)
                    elif params[0] == 'rows':
                        ds = rows_processor(link)(ds, position=position)
                    elif params[0] == 'package':
                        ds = datapackage_processor(link)(ds, position=position)
                    else:
                        assert False, 'Failed to parse function signature %r' % params
                else:
                    assert False, 'Failed to parse function signature %r' % params
            elif isinstance(link, Iterable):
                ds = iterable_loader(link)(ds, position=position)

        return ds