title: Which tool allows to generate such nice source code pictures?
body: <p>examples below. I am pretty sure that there is online free tool that can do it. But I lost a link :(</p>
  
  <p>May be someone has the link?</p>
  
  <p><a href="http://habrastorage.org/storage2/c43/58e/013/c4358e0133268ad6afa9a9f9ef11c4af.png" rel="noreferrer">http://habrastorage.org/storage2/c43/58e/013/c4358e0133268ad6afa9a9f9ef11c4af.png</a> 
  <img src="https://i.stack.imgur.com/hx1uP.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/onv8R.png" alt="enter image description here"></p>