syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"impl<'a,"}]}
source_snippet: impl<'a, 'tcx> visit::Visitor<'a, 'tcx> for IsThirPolymorphic<'a, 'tcx> {
context_after:     fn thir(&self) -> &'a thir::Thir<'tcx> {