0(1) element: null
1(2) element: PyMatchStatement
2(3,6) WRITE ACCESS: x
3(4) element: PyStatementList
4(5) element: PyExpressionStatement
5(13) READ ACCESS: y
6(7,12) refutable pattern: 42
7(8) matched pattern: 42
8(9) ASSERTTYPE ACCESS: null
9(10) element: PyStatementList
10(11) element: PyExpressionStatement
11(13) READ ACCESS: y
12(13) ASSERTTYPE ACCESS: null
13(14) element: PyExpressionStatement
14(15) READ ACCESS: z
15() element: null