{"ast_node_type":"variable","tokens":[{"end":58,"kind":"keyword","start":0,"text":"let"}]}
    let in_reg = bx.append_sibling_block("va_arg.in_reg");
    let maybe_reg = bx.append_sibling_block("va_arg.maybe_reg");
    let on_stack = bx.append_sibling_block("va_arg.on_stack");