code: def download_file(file_id, file_name):
      '''Download a file from UPLOAD_FOLDER'''
      extracted_out_dir = os.path.join(app.config['UPLOAD_FOLDER'], file_id)
      return send_file(os.path.join(extracted_out_dir, file_name)f download_file(file_id, file_name):
      '''Download a file from UPLOAD_FOLDER'''
      extracted_out_dir = os.path.join(app.config['UPLOAD_FOLDER'], file_id)
      return send_file(os.path.join(extracted_out_dir, file_name))
docs: Download a file from UPLOAD_FOLDER