syntax_data: {"ast_node_type":"other","tokens":[{"end":38,"kind":"keyword","start":0,"text":"&ExprKind::Use"}]}
source_snippet:         &ExprKind::Use { source } => {
context_before:         // This is important so that `N as usize as usize` doesn't unify with `N as usize`. (untested)
context_after:             let value_ty = body.exprs[source].ty;