0(1) element: null
1(2) element: PyMatchStatement
2(3,6) element: PyWildcardPattern
3(4) element: PyStatementList
4(5) element: PyExpressionStatement
5(7) READ ACCESS: y
6(7) ASSERTTYPE ACCESS: null
7(8) element: PyExpressionStatement
8(9) READ ACCESS: z
9() element: null