root:
             product   file:plan.py
             product   step:./plan.py

file:plan.py
               state = CONFIRMED
             creator   root:
                sink   step:./plan.py

step:./plan.py
               state = SUCCEEDED
                need = PLAN
           using_env = STEPUP_PATH_FILTER [dynamic]
             creator   root:
              source   file:plan.py
             product   step:echo 1
             product   step:echo 2

step:echo 1
               state = PENDING
                need = DEFAULT
            resource = token: 1 units
             creator   step:./plan.py

step:echo 2
               state = PENDING
                need = DEFAULT
            resource = token: 1 units
             creator   step:./plan.py
