old_contents: from flask import Flask, render_template
  from names import get_full_name
  
  
  app = Flask(__name__)
  
  
  @app.route("/")
  def index():
      return render_template('index.html', name=get_full_name())
  
  
  if __name__ == "__main__":
      app.run()
  
new_contents: import os
  from flask import Flask, render_template
  from names import get_full_name
  
  
  app = Flask(__name__)
  
  
  @app.route("/")
  def index():
      return render_template('index.html', name=get_full_name())
  
  
  if __name__ == "__main__":
      port = int(os.environ.get('PORT', 5000))
      app.run(host='0.0.0.0', port=port)
  
subject: Use environment variable PORT for flask port