code: function (other) {
          if (other instanceof tree.Dimension) {
              if (other.value > this.value) {
                  return -1;
              } else if (other.value < this.value) {
                  return 1;
              } else {
                  return 0;
              }
          } else {
              return -1;
          }
      }
docs: TODO: Perform unit conversion before comparing