Class Counted

Lib/test/test_descr.py:1232–1237

        # Test leaks
        class Counted(object):
            counter = 0    # counts the number of instances alive
            def __init__(self):
                Counted.counter += 1
            def __del__(self):
                Counted.counter -= 1
        class C(object):
            __slots__ = ['a', 'b', 'c']
        x = C()