code: def slack_message():
      
      # Incoming request format:
      # token=TOKEN
      # team_id=T0001
      # team_domain=example
      # channel_id=C12345
      # channel_name=test
      # user_id=U12345
      # user_name=Steve
      # command=/weather
      # text=94070
  
      # Verify Slack token lines up
      if request.form['token'] != SLACK_TOKEN:
          return ('Provided Slack token from message didn\'t match our server\'s Slack token. '
                  'Please double check they are aligned', 403)
  
      # Extract our text and make a card
      text = request.form['text']
      user_name = request.form['user_name']
      # Pre-emptively extract channel name before taking actions (transaction-esque)
      channel_name = request.form['channel_name']
      card = make_trello_card(name='{text} ({user_name})'.format(text=text, user_name=user_name))
  
      # Send a message to Slack about our success
      # TODO: Escape our content
      send_slack_message(channel='#{channel_name}'.format(channel_name=channel_name),
                         text='Trello card "<{url}|{text}>" created by "{user_name}"'
                         .format(url=card.url, text=text, user_name=user_name))
  
      # Reply with nothing (as the external message does more)
      return ''
docs: When we receive a message from Slack, generate a Trello card and reply