title: Gerrit Code review multiple submisions
body: <p>Im New to Gerrit,
  trying to understand the correct way to submit multiple reviews:</p>
  
  <p>i have files: a.py , b.py , c.py</p>
  
  <p>i was asked to submit each file for a separate review, 
  all files are on same branch but each file has its own commit </p>
  
  <p><strong>Branch feature:</strong>
  [CommitA: a.py] -> [CommitB:b.py] -> [CommitC:c.py]</p>
  
  <ul>
  <li>how do i submit to Gerrit for review files b.py and c.py without Gerrit including previous files in commit chain ? </li>
  <li>does Gerrit know to remove already submitted files ?</li>
  </ul>