syntax_data: {"ast_node_type":"other","tokens":[{"end":34,"kind":"keyword","start":0,"text":"PatKind::AscribeUserType"}]}
source_snippet:         PatKind::AscribeUserType {
context_before:             CanonicalUserTypeAnnotation { user_ty: Box::new(annotation), span, inferred_ty: ty };
context_after:             subpattern: pattern,