input: Write a function to create a Python Flask web application that takes user input and generates an HTML page displaying the input. The function should be named `create_flask_app` and it should return the Flask application object. The application should have a route '/' that accepts both GET and POST methods, where GET renders the `index.html` template and POST renders the `result.html` template with the user input displayed. If the input is not provided, it should not display any error and simply show an empty string as the input. 
  
  from flask import Flask, render_template, request
  
  def create_flask_app():
      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')
  
      return app
  
  assert type(create_flask_app()) == type(Flask(__name__))
  assert create_flask_app().root_path.endswith('app')
output: 
  def create_flask_app():
      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')
  
      return app
  