Inspired by the Job DSL & Build Flows plugin combo.

Currently one can only view running steps inside Workflow by digging into the particular build's details. It would be convenient if selected steps could be displayed as child nodes of the original Workflow job, in the same way Job DSL allows. The ideal interface would be the addition of 'subroutine' step taking a label parameter for display and a closure.

If such functionality should be implemented as Job DSL scripts that create Workflow jobs with CPS DSL, it is unclear what best practices to use.