{"ast_node_type":"other","tokens":[{"end":37,"kind":"keyword","start":0,"text":"[self_arg,"}]}
            [self_arg, pack_arg] => (
            [pack_arg] => (None, codegen_call_argument_operand(fx, &pack_arg.node)),
                Some(codegen_call_argument_operand(fx, &self_arg.node)),