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]
               nglob = data.txt
           explained = yes
             creator   root:
              source   file:plan.py
             product   file:analyzed.txt
             product   step:cat analyzed.txt

file:analyzed.txt
               state = CONFIRMED
             creator   step:./plan.py
                sink   step:cat analyzed.txt

step:cat analyzed.txt
               state = SUCCEEDED
                need = DEFAULT
           explained = yes
             creator   step:./plan.py
              source   file:analyzed.txt
