Class K

Lib/test/picklecommon.py:33–39

# Hashable immutable key object containing unheshable mutable data.
class K:
    def __init__(self, value):
        self.value = value

    def __reduce__(self):
        # Shouldn't support the recursion itself
        return K, (self.value,)

class WithSlots(object):
    __slots__ = ('a', 'b')