def _unstructure_mapping(self, mapping):
        """Convert a mapping of attr classes to primitive equivalents."""

        # We can reuse the mapping class, so dicts stay dicts and OrderedDicts
        # stay OrderedDicts.
        dispatch = self._unstructure_func.dispatch
        return mapping.__class__(
            (dispatch(k.__class__)(k), dispatch(v.__class__)(v))
            for k, v in mapping.items()
        )