def _unjelly_instance(self, rest):
        """
        (internal) Unjelly an instance.

        Called to handle the deprecated I{instance} token.

        @param rest: The s-expression representing the instance.

        @return: The unjellied instance.
        """
        warnings.warn_explicit(
            "Unjelly support for the instance atom is deprecated since "
            "Twisted 15.0.0.  Upgrade peer for modern instance support.",
            category=DeprecationWarning, filename="", lineno=0)

        clz = self.unjelly(rest[0])
        if not _PY3 and type(clz) is not _OldStyleClass:
            raise InsecureJelly("Legacy 'instance' found with new-style class")
        return self._genericUnjelly(clz, rest[1])

        (internal) Unjelly an instance.

        Called to handle the deprecated I{instance} token.

        @param rest: The s-expression representing the instance.

        @return: The unjellied instance.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/spread/jelly.py