0(1) element: null
1(2) element: PyMatchStatement
2(5) element: PyWildcardPattern
3(4,7) refutable pattern: 42
4(5) matched pattern: 42
5(6) element: PyExpressionStatement
6(7) READ ACCESS: y
7(8) element: PyExpressionStatement
8(9) READ ACCESS: z
9() element: null