{"ast_node_type":"function","tokens":[{"end":84,"kind":"keyword","start":0,"text":"fn"}]}
    fn check_decl_self_param(&self, fn_decl: &FnDecl, self_semantic: SelfSemantic) {
        if let (SelfSemantic::No, [param, ..]) = (self_semantic, &*fn_decl.inputs) {