input: Write a function to implement a web application in Python using Flask that will take user input and generate an HTML page with the input. The function should define the necessary routes and templates. If the user submits input via a POST request, the application should render an HTML page displaying the input. Otherwise, it should serve the initial form.
  
  def create_flask_app():
      from flask import Flask, render_template, request
  
      app = Flask(__name__)
  
      @app.route('/', methods=['GET', 'POST'])
      def home():
          if request.method == 'POST':
              input_text = request.form.get('input_text')
              return render_template('result.html', input_text=input_text)
          return render_template('index.html')
  
      if __name__ == '__main__':
          app.run(debug=True)
  
      return app
  
  assert create_flask_app() is not None
  # Should initialize a Flask app
  assert create_flask_app().debug == True
  # Should run in debug mode
  assert create_flask_app().route_functions['home'].methods == ['GET', 'POST']
  # Should have a route named 'home' that accepts GET and POST requests
output: 
  def create_flask_app():
      from flask import Flask, render_template, request
  
      app = Flask(__name__)
  
      @app.route('/', methods=['GET', 'POST'])
      def home():
          if request.method == 'POST':
              input_text = request.form.get('input_text')
              return render_template('result.html', input_text=input_text)
          return render_template('index.html')
  
      if __name__ == '__main__':
          app.run(debug=True)
  
      return app
  