0(1) element: null
1(2) element: PyMatchStatement
2(3,14) refutable pattern: Class(1, attr=foo.bar)
3(4) READ ACCESS: Class
4(5,14) refutable pattern: 1
5(6) matched pattern: 1
6(7,14) refutable pattern: attr=foo.bar
7(8,14) refutable pattern: foo.bar
8(9) READ ACCESS: foo
9(10) matched pattern: foo.bar
10(11) matched pattern: attr=foo.bar
11(12) matched pattern: Class(1, attr=foo.bar)
12(13) element: PyExpressionStatement
13(14) READ ACCESS: x
14(15) element: PyExpressionStatement
15(16) READ ACCESS: y
16() element: null