syntax_data: {"ast_node_type":"other","tokens":[{"end":26,"kind":"keyword","start":0,"text":"self_ty:"}]}
source_snippet:         self_ty: Ty<'tcx>,
context_before:         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
context_after:         trait_ref: Option<ty::TraitRef<'tcx>>,