syntax_data: {"ast_node_type":"variable","tokens":[{"end":50,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let ref_expr = self.thir.exprs.push(Expr {
context_before:         let fun_ty = self.thir[fun].ty;
context_after:             temp_lifetime: TempLifetime { temp_lifetime, backwards_incompatible },