syntax_data: {"ast_node_type":"impl","tokens":[{"end":49,"kind":"keyword","start":0,"text":"iter:"}]}
source_snippet:         iter: impl IntoIterator<Item = Ty<'tcx>>,
context_before:         tcx: TyCtxt<'tcx>,
context_after:     ) -> NeedsDropResult<Vec<Ty<'tcx>>> {