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

file:plan.py
               state = CONFIRMED
             creator   root:
                sink   step:./plan.py

step:./plan.py
               state = SUCCEEDED
                need = PLAN
           using_env = STEPUP_PATH_FILTER [dynamic]
           explained = yes
             creator   root:
              source   file:plan.py
             product   file:asource1.txt
             product   file:asource2.txt
             product   file:work.py
             product   step:./work.py > log.txt
             product   step:cp -p asource1.txt data1.txt
             product   step:cp -p asource2.txt data2.txt

step:./work.py > log.txt
               state = SUCCEEDED
                need = DEFAULT
           explained = yes
             creator   step:./plan.py
              source   file:data1.txt
              source   file:data2.txt [dynamic]
              source   file:work.py
             product   file:log.txt
                sink   file:log.txt

file:data1.txt
               state = BUILT
             creator   step:cp -p asource1.txt data1.txt
              source   step:cp -p asource1.txt data1.txt
                sink   step:./work.py > log.txt

file:work.py
               state = CONFIRMED
             creator   step:./plan.py
                sink   step:./work.py > log.txt

file:log.txt
               state = BUILT
             creator   step:./work.py > log.txt
              source   step:./work.py > log.txt

file:asource1.txt
               state = CONFIRMED
             creator   step:./plan.py
                sink   step:cp -p asource1.txt data1.txt

file:asource2.txt
               state = CONFIRMED
             creator   step:./plan.py
                sink   step:cp -p asource2.txt data2.txt

step:cp -p asource1.txt data1.txt
               state = SUCCEEDED
                need = DEFAULT
           explained = yes
             creator   step:./plan.py
              source   file:asource1.txt
             product   file:data1.txt
                sink   file:data1.txt

step:cp -p asource2.txt data2.txt
               state = SUCCEEDED
                need = DEFAULT
           explained = yes
             creator   step:./plan.py
              source   file:asource2.txt
             product   file:data2.txt
                sink   file:data2.txt

file:data2.txt
               state = BUILT
             creator   step:cp -p asource2.txt data2.txt
              source   step:cp -p asource2.txt data2.txt
                sink   step:./work.py > log.txt
