def mrs(self):
        """
        Deserialize and return an Mrs object for simplemrs or
        JSON-formatted MRS data; otherwise return the original string.
        """
        mrs = self.get('mrs')
        if mrs is not None:
            if isinstance(mrs, dict):
                mrs = Mrs.from_dict(mrs)
            elif isinstance(mrs, stringtypes):
                mrs = simplemrs.loads_one(mrs)
        return mrs