code: def images():
      
      if request.method == 'POST':
          file_upload = request.files['file']
          if file_upload:
              image = dict()
              image['filename'] = secure_filename(file_upload.filename)
              full_path = os.path.join(session['img_input_dir'],
                                       image['filename'])
              file_upload.save(full_path)
              image['uid'] = session['image_uid_counter']
              session['image_uid_counter'] += 1
              current_app.logger.debug('File %d is saved as %s',
                                       image['uid'],
                                       image['filename'])
              session['image_list'].append(image)
              return jsonify(ok="true", file=image['filename'], uid=image['uid'])
          return jsonify(ok="false")
      if request.method == 'GET':
          return jsonify(images=session['image_list'])
docs: Upload images via REST interface
  
      Check if file upload was successful and sanatize user input.
  
      TODO: return file URL instead of filename