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

file:./
               state = STATIC
          created by   root:
            supplies   (file:nonexisting/)
            supplies   file:plan.py
            supplies   step:runpy ./demo.py
            supplies   step:runpy ./plan.py

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

step:runpy ./plan.py
               state = SUCCEEDED
             env_var = STEPUP_PATH_FILTER [amended]
          created by   root:
            consumes   file:./
            consumes   file:plan.py
             creates   step:runpy ./demo.py

step:runpy ./demo.py
               state = PENDING
             env_var = STEPUP_PATH_FILTER [amended]
          created by   step:runpy ./plan.py
            consumes   (file:nonexisting/) [amended]
            consumes   file:./
             creates   file:nonexisting/foo.out
            supplies   file:nonexisting/foo.out [amended]

(file:nonexisting/)
               state = AWAITED
            consumes   file:./
            supplies   file:nonexisting/foo.out
            supplies   step:runpy ./demo.py

file:nonexisting/foo.out
               state = AWAITED
          created by   step:runpy ./demo.py
            consumes   (file:nonexisting/)
            consumes   step:runpy ./demo.py
