new_contents: import os
  # We'll render HTML templates and access data sent by POST
  # using the request object from flask. Redirect and url_for
  # will be used to redirect the user once the upload is done
  # and send_from_directory will help us to send/show on the
  # browser the file that the user just uploaded
  from flask import Flask, render_template, request, redirect, url_for, send_from_directory
  from werkzeug import secure_filename
  
  # Initialize the Flask application
  app = Flask(__name__)
  
  # This is the path to the upload directory
  app.config['UPLOAD_FOLDER'] = 'uploads/'
  # These are the extension that we are accepting to be uploaded
  app.config['ALLOWED_EXTENSIONS'] = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'])
  
  # For a given file, return whether it's an allowed type or not
  def allowed_file(filename):
      return '.' in filename and \
             filename.rsplit('.', 1)[1] in app.config['ALLOWED_EXTENSIONS']
  
  # This route will show a form to perform an AJAX request
  # jQuery is loaded to execute the request and update the
  # value of the operation
  @app.route('/')
  def index():
      return render_template('index.html')
  
  
  # Route that will process the file upload
  @app.route('/upload', methods=['POST'])
  def upload():
      # Get the name of the uploaded file
      file = request.files['file']
      # Check if the file is one of the allowed types/extensions
      if file and allowed_file(file.filename):
          # Make the filename safe, remove unsupported chars
          filename = secure_filename(file.filename)
          # Move the file form the temporal folder to
          # the upload folder we setup
          file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
          # Redirect the user to the uploaded_file route, which
          # will basicaly show on the browser the uploaded file
          return redirect(url_for('uploaded_file',
                                  filename=filename))
  
  # This route is expecting a parameter containing the name
  # of a file. Then it will locate that file on the upload
  # directory and show it on the browser, so if the user uploads
  # an image, that image is going to be show after the upload
  @app.route('/uploads/<filename>')
  def uploaded_file(filename):
      return send_from_directory(app.config['UPLOAD_FOLDER'],
                                 filename)
  
  if __name__ == '__main__':
      app.run(
          host="0.0.0.0",
          port=int("8080"),
          debug=True
      )
  
  
subject: Create app.py