syntax_data: {"ast_node_type":"function","tokens":[{"end":70,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn ty_for_param(&self, p: I::ParamTy, source_ty: I::Ty) -> I::Ty {
context_before: impl<'a, I: Interner> ArgFolder<'a, I> {
context_after:         // Look up the type in the args. It really should be in there.