from _testcapi import with_tp_del

@with_tp_del
class Uncollectable(object):
    """Create a reference cycle with multiple __del__ methods.

    An object in a reference cycle will never have zero references,
    and so must be garbage collected.  If one or more objects in the
    cycle have __del__ methods, the gc refuses to guess an order,
    and leaves the cycle uncollected."""
    def __init__(self, partner=None):
        if partner is None:
            self.partner = Uncollectable(partner=self)
        else:
            self.partner = partner
    def __tp_del__(self):
        pass

obj = Uncollectable()