title: Show alert in bot with python-telegram-bot
body: <p>in a telegram bot written with python-telegram-bot, I have some keyboard buttons and, when I click on one of them, I would like an alert to be shown, like here:
  <a href="https://i.stack.imgur.com/MGRHX.png" rel="nofollow noreferrer">alert screenshot</a></p>
  <p>However, it doesn't do anything when I click on the buttons and I can't figure out what's wrong.
  Thank you!</p>
  <p>Below my code:</p>
  <pre><code>from telegram import InlineKeyboardButton, InlineKeyboardMarkup
  from telegram.ext import (
      Updater,
      CommandHandler,
      CallbackQueryHandler,
  )
  
  
  token = 'XXX'
  updater = Updater(token=token, use_context=True)
  dispatcher = updater.dispatcher
  
  
  def start(update, context):
      keyboard = [
          [
              InlineKeyboardButton(&quot;dog&quot;, callback_data='dog'),
              InlineKeyboardButton(&quot;cat&quot;, callback_data='cat'),
          ],
      ]
  
      reply_markup = InlineKeyboardMarkup(keyboard)
  
      context.bot.send_message(
          chat_id=update.effective_chat.id,
          text=f'Hello {update.message.chat.first_name}!',
          reply_markup=reply_markup,
      )
  
  
  def buttons(update, context):
      query = update.callback_query
  
      query.answer()
  
      if query.data == 'cat':
          context.bot.answer_callback_query(callback_query_id=query.id, text='you chose cat', show_alert=True)
      elif query.data == 'dog':
          context.bot.answer_callback_query(callback_query_id=query.id, text='you chose dog', show_alert=True)
  
  
  start_handler = CommandHandler('start', start)
  dispatcher.add_handler(start_handler)
  
  buttons_handler = CallbackQueryHandler(buttons)
  dispatcher.add_handler(buttons_handler)
  
  
  updater.start_polling()```
  </code></pre>