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:data/sub/inp.txt
             product   step:cat data/sub/inp.txt > data/sub/out.txt

file:data/sub/inp.txt
               state = MISSING
             creator   step:./plan.py
                sink   step:cat data/sub/inp.txt > data/sub/out.txt

step:cat data/sub/inp.txt > data/sub/out.txt
               state = PENDING
                need = DEFAULT
             creator   step:./plan.py
              source   file:data/sub/inp.txt
             product   file:data/sub/out.txt
                sink   file:data/sub/out.txt

file:data/sub/out.txt
               state = PLANNED
             creator   step:cat data/sub/inp.txt > data/sub/out.txt
              source   step:cat data/sub/inp.txt > data/sub/out.txt
