input: Write a python function to register a user and card using Flask framework.
  assert register_user_card('POST', {'username': 'JohnDoe', 'card': '1234567890'}) == ('register.html', {'success': True})
  assert register_user_card('GET', {}) == 'register.html'
output: from flask import Flask, request, render_template
  
  app = Flask(__name__)
  
  @app.route('/register', methods=['GET', 'POST'])
  def register_user_card():
      if request.method == 'POST':
          username = request.form.get('username')
          card = request.form.get('card')
          if username and card:
              # Here you would typically save the user and card information to the database
              return render_template('register.html', success=True)
      return render_template('register.html')