code: private void setLength(double length) {
          switch (type) {
              case BOX:
                  box.setHeight(length);
                  break;
              case CYLINDER:
                  cylinder.setHeight(length);
                  break;
              default:
                  break;
          }
      }
docs: Sets the length of the line. This is only used internally to shape the
  line correctly.
  
  @param length Length of the line.