title: How can I update data with google appengine-python-ndb?
body: <p>I have a User table and there is two fields. I want to update one field every day. How can I do this?
  My codes:</p>
  
  <pre><code>class User(ndb.Model):
      username = ndb.StringProperty()
      something = ndb.StringProperty(repeated=True)
      created_date = ndb.DateTimeProperty(auto_now_add=True)
      updated_date = ndb.DateTimeProperty(auto_now_add=True)
  </code></pre>
  
  <p>I want to change something field but how can I do this ?</p>