syntax_data: {"ast_node_type":"variable","tokens":[{"end":58,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let annotation = CanonicalUserTypeAnnotation {
context_before:             debug!("lower_variant_or_leaf: kind={:?} user_ty={:?} span={:?}", kind, user_ty, span);
context_after:                 user_ty: Box::new(user_ty),