code: public INDArray getRange() {
          if (range == null) {
              try (MemoryWorkspace ws = Nd4j.getMemoryManager().scopeOutOfWorkspaces()) {
                  range = upper.sub(lower);
              }
          }
          return range;
      }
docs: Get the feature wise
  range for the statistics.
  Note that this is a lazy getter.
  It is only computed when needed.
  @return the feature wise range
  given the min and max