title: How does repeated property indexing work in datastore with ndb
body: <p>How does the indexing for repeated/list property work, I read somewhere that adding to list will just add an index, and will not count as modified index. Is this still correct?</p>
  
  <p>Is it same for deleting from the list, will deleting a value in list just remove that single index and count as 2 writes?</p>
  
  <p>If what I understand is correct then this</p>
  
  <pre><code>class MyModel(ndb.Model):
      my_list = ndb.IntegerProperty(repeated=True)
  
  e = ndb.Key(MyModel, 100).get()
  e.my_list.append(50)
  e.put()
  e.my_list.append(25)
  e.put()
  e.my_list.remove(50)
  e.put()
  </code></pre>
  
  <p>the updates are, 
  1 write + 2 index write,
  then another,
  1 write + 2 index write,
  then,
  1 write + 2 index write for deletion.</p>
  
  <p>Is that correct?</p>
  
  <p>My final question about this is the 5000 index per entity limit still exists?
  Cause I tried running 10k localhost it seems to work.</p>
  
  <p>Additional:</p>
  
  <pre><code>e.my_list.insert(10)
  e.put()
  </code></pre>
  
  <p>Does this just add another index? or the index holds the list index in it making this adjust the whole list?</p>