$bot_url="https://xxxx/conversation_start.php";
$no_answer="ditulis dengan jawaban Salah Program-O";
$message = $event['message'];

$json = file_get_contents($bot_url."?convo_id=&say=".rawurlencode($message['text']));
if($json) {
  $obj = json_decode($json);
  if($obj->botsay!=$no_answer)
  {
    $message = $obj->botsay;
  } else {
    $message = "Maaf, saya belum bisa jawab";
  }
}