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   file:line.txt
             product   step:cat line.txt >> log.txt; exit 1

file:line.txt
               state = CONFIRMED
             creator   step:./plan.py
                sink   step:cat line.txt >> log.txt; exit 1

step:cat line.txt >> log.txt; exit 1
               state = FAILED
                need = DEFAULT
             creator   step:./plan.py
              source   file:line.txt
             product   file:log.txt
                sink   file:log.txt

file:log.txt
               state = OUTDATED
             creator   step:cat line.txt >> log.txt; exit 1
              source   step:cat line.txt >> log.txt; exit 1
