text: from flask import Flask, request
  
  app = Flask(__name__)
  
  @app.route('/hello')
  def say_hello():
      return "Hello, World!"
  
  @app.route('/user/<username>')
  def say_hello_var(username):
      return 'Hi, ' + username
  
  @app.route('/double/<int:the_number>')
  def double(the_number):
      return str(the_number * 2)
  
  @app.route('/double')
  def double2():
      the_number = request.args.get('number')
      the_number = int(the_number)
      return str(the_number * 2)
  
  @app.route('/search')
  def search_page():
      name = request.args.get('name')
      category = request.args.get('category')
      return 'You searched for ' + name + ' in the category ' + category
  
  @app.route('/search_form')
  def search_form():
      return """
      <form action='/search'>
          Type in the product name: <input type='text' name='name'>
          <br>
          Type in the category: <input type='text' name='category'>
          <br>
          <input type='submit'>
      </form>
      """
  
  @app.route('/login', methods=['POST'])
  def login():
      username = request.form.get('username')
      password = request.form.get('password')
      return "Username is " + username + ", password is " + password
  
  @app.route('/login_form')
  def login_form():
      return """
      <form action='/login' method='POST'>
          Username: <input type='text' name='username'>
          <br>
          Password: <input type='password' name='password'>
          <br>
          <input type='submit'>
      </form>
      """