syntax_data: {"ast_node_type":"other","tokens":[{"end":72,"kind":"keyword","start":0,"text":"(ty::GenericArgKind::Lifetime(_),"}]}
source_snippet:                 (ty::GenericArgKind::Lifetime(_), ty::Bivariant) => arg,
context_before:             std::iter::zip(args.iter(), variances.iter()).map(|(arg, v)| match (arg.kind(), v) {
context_after:                 (ty::GenericArgKind::Lifetime(lt), _) => f(lt).into(),