title: Vim folding - Close all children recursively under cursor
body: <p>I know how to open all folds under cursor with <code>zO</code>.</p>
  
  <p>But how to do reverse?</p>
  
  <p>I want something like <code>za</code> does, but also with recursivity.</p>
  
  <p>PS. I know there is <code>zC</code>, but it closes all parent folds in relation to current line and I want to close children.</p>