title: pull push atomic operation?
body: <p>I have a document with 2 arrays, I want to move one element from one array to the other, I tried this on the console and it works:     </p>
  
  <pre><code>db.examplecol.update({_id: ObjectId("5056b4b2b9f53a21385076c5")} , {'$pull':{setA:3}, '$push':   {setB:3}})
  </code></pre>
  
  <p>But I haven't seen yet an example of 2 updates in a single command. My question is if this is an atomic operation? If something goes wrong in the middle of this operation, do I have the risk of "losing" my element by it have been pulled but not pushed?</p>