code: def persistent(self):
      if self._pclass_evolver_data_is_dirty:
          return self._pclass_evolver_original.__class__(
              _factory_fields=self._factory_fields,
              **self._pclass_evolver_data,
          )
  
      return self._pclass_evolver_original
  
imports: import six
  from pyrsistent._checked_types import InvariantException, CheckedType, _restore_pickle, store_invariants
  from pyrsistent._field_common import set_fields, check_type, is_field_ignore_extra_complaint, PFIELD_NO_INITIAL, serialize, check_global_invariants
  from pyrsistent._transformations import transform
label_desc: Use image node_id 7 for calling the _PClassEvolver obj's underlying member method code with example usage: obj.persistent() and returns: self, self