Is possible nest steps in steps?

[daassh]

Just like jenkins blueocean:

I have try by this code

<ul class="steps">
  <li class="step step-primary">1</li>
    <ul class="steps steps-vertical">
    <li class="step step-primary">2-1</li>
    <li class="step step-primary">2-2</li>
  </ul>
  <li class="step step-primary">3</li>
</ul>

and I got this

[saadeghi]

I think you should use a professional flowchart library for that.