How do I create an “hourglass” input like the one in the signature in this post in the Block Plugin?

It's an empty boolean block

<::#0ff>

here the edges are cut off because the bounding box is too small (which is actually why it's turned inside-out), to make the entire thing appear you need to put it inside another block

move <::#0ff> steps

Hello <::0ff> steps

Thank you!