syntax_data: {"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                             let annotation = CanonicalUserTypeAnnotation {
context_before:                             debug!("mirror_stmts: user_ty={:?}", user_ty);
context_after:                                 user_ty: Box::new(user_ty),