0(1) element: null
1(2) element: PyMatchStatement
2(3,9) refutable pattern: [1 | x]
3(4,5) refutable pattern: 1
4(7) matched pattern: 1
5(6) WRITE ACCESS: x
6(7) matched pattern: [1 | x]
7(8) element: PyExpressionStatement
8(9) READ ACCESS: y
9(10) element: PyExpressionStatement
10(11) READ ACCESS: z
11() element: null