syntax_data: {"ast_node_type":"variable","tokens":[{"end":67,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let closure_ty = self.typeck_results.expr_ty(expr);
context_before:             hir::ExprKind::Closure(hir::Closure { .. }) => {
context_after:                 let (def_id, args, movability) = match *closure_ty.kind() {