{"ast_node_type":"other","tokens":[{"end":44,"kind":"keyword","start":0,"text":"//"}]}
                    // first parameter type.
                    // When `sig_tys.len() == 1` the first type is the return type, not the
                    Some(ty) if sig_tys.len() > 1 => ty.assert_ty_ref(Interner).clone(),