Return None or user-provided CountRelatives object.

def get_rcntobj(self):
        """Return None or user-provided CountRelatives object."""
        # rcntobj value in kws can be: None, False, True, CountRelatives object
        if 'rcntobj' in self.kws:
            rcntobj = self.kws['rcntobj']
            if isinstance(rcntobj, CountRelatives):
                return rcntobj
            return CountRelatives(
                self.go2obj,  # Subset go2obj contains only items needed by go_sources
                self.relationships,
                dcnt='dcnt' in self.kw_elems,
                go2letter=self.kws.get('go2letter'))