title: Command for toggling line numbers in vi
body: <p>I know</p>
  
  <pre><code>:set number
  </code></pre>
  
  <p>and</p>
  
  <pre><code>:set nonumber
  </code></pre>
  
  <p>I want to know whether there is any command in vi/vim</p>
  
  <pre><code>:set togglenumber
  </code></pre>
  
  <p>to display line number if the line numbers is not showing or hiding line numbers if line numbers is showing.</p>