static Steppable nlLogic_fillBattleSpace_steppable(final NLLogicChecker_v2 c, final Collector<RuleWithParams> battleSpace, final bool debug) {
  ret new SplittableSteppable {
    volatile bool done;
    SplittableSteppable inner;
    
    {
      VF2<IfThen, NLLogicChecker_v2.Matching> onRuleFired = voidfunc(IfThen rule, NLLogicChecker_v2.Matching m) {
        if (battleSpace.add(new RuleWithParams(rule, m.matches)))
          set done;
      };
      VF4<IfThen, NLLogicChecker_v2.Matching, L<Exp>, Exp> onRuleFailed = voidfunc(IfThen rule, NLLogicChecker_v2.Matching m, L<Exp> satisfiedConditions, Exp remaining) {
        //print("satisfied conditions: " + satisfiedConditions);
        if (battleSpace.add(new FailedRule(rule, m.matches, cloneListOrNull(nullIfEmpty(satisfiedConditions)), remaining)))
          set done;
      };
      
      print("Iterating over " + n2(c.rules, "rule"));
      applyNLLogicFacts_v4_iterate_steppable_verbose.set(debug);
      inner = applyNLLogicFacts_v4_iterate_steppable(c, onRuleFired, onRuleFailed, c.rules);
    }
    
    public bool step() {
      ret !done && inner.step();
    }
    
    public L<Steppable> split(int n) {
      ret map(inner.split(n), func(final Steppable inner2) -> Steppable {
        ret new Steppable {
          public bool step() { ret !done && inner2.step(); }
        };
      });
    }
  };
}

Began life as a copy of #1018337