def change_and_save(self, update_only_changed_fields=False, **changed_fields):
change_and_save(self, update_only_changed_fields=update_only_changed_fields, **changed_fields)<EOL>return self<EOL>
Changes a given `changed_fields` on this object, saves it and returns itself.
:param update_only_changed_fields: only changed fields will be updated in the database.
:param changed_fields: fields to change.
:return: self