code: private List[] findEquatedIdentifiers() {
      List[] ans = null;
      for (int i = 0; i < tmpSimpleTests.size(); i++) {
        SimpleTest cand = (SimpleTest) tmpSimpleTests.get(i);
        if (cand.getKind() == SimpleTest.NULL) {
          if (ans == null)
            ans = new List[] { new ArrayList(), new ArrayList() };
          ans[0].add(cand.getIdentifier().getName());
          ans[1].add(null);
        }
        else {
          Object candValue = cand.getValue();
          if (candValue != null) {
            if (ans == null)
              ans = new List[] { new ArrayList(), new ArrayList() };
            ans[0].add(cand.getIdentifier().getName());
            ans[1].add(candValue);
          }
        }
      }
      return ans;
    }
docs: that these can be removed from tmpResidual.  Return null if there are none.