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

file:plan.py
               state = STATIC
          created by   root:
            consumes   file:./
            supplies   step:./plan.py

file:./
               state = STATIC
          created by   root:
            supplies   file:README.md
            supplies   file:inventory.txt
            supplies   file:plan.py
            supplies   step:./plan.py
            supplies   step:rr-make-inventory README.md -o inventory.txt

step:./plan.py
               state = SUCCEEDED
          inp_digest = same
          created by   root:
            consumes   file:./
            consumes   file:plan.py
             creates   file:README.md
             creates   step:rr-make-inventory README.md -o inventory.txt

file:README.md
               state = STATIC
          created by   step:./plan.py
            consumes   file:./
            supplies   step:rr-make-inventory README.md -o inventory.txt

step:rr-make-inventory README.md -o inventory.txt
               state = SUCCEEDED
          created by   step:./plan.py
            consumes   file:./
            consumes   file:README.md
             creates   file:inventory.txt
            supplies   file:inventory.txt

file:inventory.txt
               state = BUILT
          created by   step:rr-make-inventory README.md -o inventory.txt
            consumes   file:./
            consumes   step:rr-make-inventory README.md -o inventory.txt
