code: private boolean isRotatable(final int lit) {
          // Unit propagated literals cannot be rotatable
          if (v(var(lit)).reason() != null) {
              return false;
          }
          // A rotatable literal MUST NOT be unit
          for (final MSWatcher watcher : this.watches.get(not(lit))) {
              if (isUnit(lit, watcher.clause())) {
                  return false;
              }
          }
          return true;
      }
docs: Tests the given literal whether it is rotatable in the current model.
  @param lit literal to test
  @return {@code true} if the literal is rotatable, otherwise {@code false}