syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"Some(u)"}]}
source_snippet:                     Some(u) => panic!("const mapped to unexpected kind: {u:?}"),
context_before:                     Some(GenericArgKind::Const(c1)) => c1,
context_after:                     None => {