old_contents: from flask import Flask
  from flask.ext.pymongo import PyMongo
  
  app = Flask(__name__)
  mongo = PyMongo(app)
  
  
new_contents: from flask import Flask
  from flask_pymongo import PyMongo
  
  app = Flask(__name__)
  mongo = PyMongo(app)
  
  
subject: Use non-deprecated import syntax.