syntax_data: {"ast_node_type":"impl","tokens":[{"end":44,"kind":"keyword","start":0,"text":")"}]}
source_snippet:     ) -> impl Iterator<Item = Param<'tcx>> {
context_before:         body: &'tcx hir::Body<'tcx>,
context_after:         let fn_sig = self.typeck_results.liberated_fn_sigs()[owner_id];