class Array:
    def __init__(self, size=32):
        self._size = size
        self._items = [None]*32
    def __getitem__(self, index):
        return self._items[index]
    def __setitem__(self, index, value):
        self._items[index] = value
    def __len__(self):
        return self._size
    def clear(self, value=None):
        for i in range(len(self._items)):
            self._items[i] = value
    def __iter__(self):
        for i in self._items:
            yield i
def test_array():
    size = 10
    a = Array(size)
    a[0] = 1
    assert a[0] == 1
    a.clear()
    assert a[0] is None
    print("test successful")
if __name__ == "__main__":
    test_array()