anchor.diff:                  [
                       {"Y1",
                           {'if',
  -                            [{lte({'#', TimeD}, 0), "X1"}],
  +                            lte({'#', TimeD}, 0),
  +                            "X1",
                               {'@',
                                   plus(
                                       plus({'@', "Y1", {t, [{XD, times({'#', XD}, 2)},
  
positive.code:                 }
              },
              {"B", {'if',
                      [{tand(gte({'#', SpaceD}, 1),
                             lte({'#', SpaceD}, 1024)),
                        {'#', SpaceD}}],
                      1
                  }
              }
  
negative.code:         {wheredim,
              {wherevar, "A", [
              {"A", {'if',
                      lte({'#', TimeD}, 0),
                      "B",
                      {'@',
                          plus({'@', "A", {t, [{SpaceD,      times({'#', SpaceD}, 2    )}]}},
                               {'@', "A", {t, [{SpaceD, plus(times({'#', SpaceD}, 2), 1)}]}}),
  