{"ast_node_type":"variable","tokens":[{"end":67,"kind":"keyword","start":0,"text":"let"}]}
        let mir_output_ty = self.body.local_decls[RETURN_PLACE].ty;
        // Return types are a bit more complex. They may contain opaque `impl Trait` types.
        let output_span = self.body.local_decls[RETURN_PLACE].source_info.span;