I read that too, but couldn't fathom what they meant. Still, I'm not sure what they mean by "prefix argument." And why does (shell-command "uuidgen" t) produces two outputs? For other readers, this is what they look like in *scratch*
(shell-command "uuidgen" t)
2827
b5da7e0a-84c0-4db8-91f3-871b681f3022
(org-id-uuid)
"0bb7a4e1-9fc2-4428-b8de-a2d9ef5c56ab"
Also, does anyone know how I could have done this by "advise"-ing a function in org-mode tempo templates? I could never figure out what function was actually handling the <...-TAB.