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

file:./
               state = STATIC
          created by   root:
            supplies   file:missing.txt
            supplies   file:plan.py
            supplies   file:step.py
            supplies   step:./plan.py
            supplies   step:./step.py
            supplies   step:echo Will be deleted by accident > missing.txt

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

step:./plan.py
               state = SUCCEEDED
          created by   root:
            consumes   file:./
            consumes   file:plan.py
             creates   file:step.py
             creates   step:./step.py
             creates   step:echo Will be deleted by accident > missing.txt

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

step:./step.py
               state = FAILED
          created by   step:./plan.py
            consumes   file:./
            consumes   file:missing.txt [amended]
            consumes   file:step.py

step:echo Will be deleted by accident > missing.txt
               state = SUCCEEDED
          created by   step:./plan.py
            consumes   file:./
             creates   file:missing.txt
            supplies   file:missing.txt

file:missing.txt
               state = BUILT
          created by   step:echo Will be deleted by accident > missing.txt
            consumes   file:./
            consumes   step:echo Will be deleted by accident > missing.txt
            supplies   step:./step.py
