rough-minister-58256
06/13/2017, 10:26 PMtests/python/pants_test/engine/examples/planners.py
has a bunch of example/prototype rules, but in general they’re a bit scattered. can scan for usages of pants.engine.rules.{SingletonRule,TaskRule}
and pants.engine.selectors.{Select,SelectDependencies,SelectProjection,SelectVariant}