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

file:plan.py
               state = CONFIRMED
              digest = 52f76e6e 44aa9a2f 2495d98a bc23e312 ac826bda eeaec4cf 28d9fe49 ec7603c9
             creator   root:
                sink   step:./plan.py

step:./plan.py
               state = RUNNING
                need = PLAN
             creator   root:
              source   file:plan.py
             product   step:grep Coffee story.txt
             product   step:printf "Monday frown\nCoffee smile\n" > story.txt

step:printf "Monday frown\nCoffee smile\n" > story.txt
               state = RUNNING
                need = DEFAULT
             creator   step:./plan.py
             product   file:story.txt
                sink   file:story.txt

file:story.txt
               state = PLANNED
             creator   step:printf "Monday frown\nCoffee smile\n" > story.txt
              source   step:printf "Monday frown\nCoffee smile\n" > story.txt
                sink   step:grep Coffee story.txt

step:grep Coffee story.txt
               state = PENDING
                need = DEFAULT
             creator   step:./plan.py
              source   file:story.txt
