syntax_data: {"ast_node_type":"other","tokens":[{"end":40,"kind":"keyword","start":0,"text":"tuple_arguments:"}]}
source_snippet:     tuple_arguments: TupleArgumentsFlag,
context_before:     sig: ty::PolyFnSig<'tcx>,
context_after: ) -> ty::Binder<'tcx, (ty::TraitRef<'tcx>, Ty<'tcx>)> {