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:trigger.txt
             product   step:./sink.py
             product   step:./source.sh

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

step:./source.sh
               state = SUCCEEDED
                need = DEFAULT
             creator   step:./plan.py
             product   file:data.txt
                sink   file:data.txt

file:data.txt
               state = BUILT
             creator   step:./source.sh
              source   step:./source.sh
                sink   step:./sink.py

step:./sink.py
               state = SUCCEEDED
                need = DEFAULT
           using_env = STEPUP_PATH_FILTER [dynamic]
             creator   step:./plan.py
              source   file:data.txt [dynamic]
              source   file:trigger.txt
