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

file:./
               state = STATIC
          created by   root:
            supplies   file:plan.py
            supplies   file:vol.txt
            supplies   step:./plan.py
            supplies   step:echo blub blub > vol.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   step:echo blub blub > vol.txt

step:echo blub blub > vol.txt
               state = SUCCEEDED
          created by   step:./plan.py
            consumes   file:./
             creates   file:vol.txt
            supplies   file:vol.txt

file:vol.txt
               state = VOLATILE
          created by   step:echo blub blub > vol.txt
            consumes   file:./
            consumes   step:echo blub blub > vol.txt
