input: Write a function to create a web application in Python using Flask that will take user input and generate an HTML page with the input. When the user submits the input, it should be displayed on a new page. If no input is provided, the application should display a default welcome page.
  
  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')
      
      return app
  
  app = create_flask_app()
  if __name__ == '__main__':
      app.run(debug=True)
  
  # result.html file
  <html>
   <body>
    <h1>Your Input: </h1>
    <p>{{input_text}}</p>
   </body>
  </html>
  
  assert create_flask_app()!=None
  assert isinstance(create_flask_app(), Flask)
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')
      
      return app