input: Write a python function to add a message to a list using Flask and UUID.
  assert add_message({'text': 'Hello World'})['data']['text'] == 'Hello World'
  assert add_message({'text': 'Another message'})['message'] == 'Added message'
  assert len(messages) == 2
output: from flask import Flask, request, jsonify
  import uuid
  
  app = Flask(__name__)
  messages = []
  
  @app.route('/add_message', methods=['POST'])
  def add_message():
      message_data = request.get_json()
      new_message = {
          'id': str(uuid.uuid4()),
          'text': message_data['text']
      }
      messages.append(new_message)
      response = {
          'message': 'Added message',
          'data': new_message
      }
      return jsonify(response)