input: Write a function to create a Flask web application in Python that takes user input and generates an HTML page displaying the input. The function should return a Flask application object. Function should handle GET and POST requests appropriately, rendering a template for the home page and another template for displaying the user input. 
  assert create_web_app("Your Input:") is not None
  assert create_web_app("").name == "__main__"
output: def create_web_app(placeholder_text):
      from flask import Flask, request, render_template
  
      app = Flask(__name__)
  
      @app.route('/', methods=['GET', 'POST'])
      def home():
          if request.method == 'POST':
              user_input = request.form['user_input']
              return render_template('display.html', user_input=user_input)
          return render_template('home.html', placeholder_text=placeholder_text)
  
      return app