0(1) element: null
1(2) element: PyMatchStatement
2(3) refutable pattern: Class(1, attr=foo.bar)
3(4,15) READ ACCESS: Class
4(5,15) refutable pattern: 1
5(6) matched pattern: 1
6(7,15) refutable pattern: attr=foo.bar
7(8) refutable pattern: foo.bar
8(9,15) 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: PyStatementList
13(14) element: PyExpressionStatement
14(16) READ ACCESS: x
15(16) ASSERTTYPE ACCESS: null
16(17) element: PyExpressionStatement
17(18) READ ACCESS: y
18() element: null