code: @Override
      public void onRangeChange(int start, int end) {
          if (end - start < 4) {
              throw new IllegalArgumentException(
                      "pls use OnePlusNLayoutHelper instead of OnePlusNLayoutHelperEx which childcount <= 5");
          }
          if (end - start > 6) {
              throw new IllegalArgumentException(
                      "OnePlusNLayoutHelper only supports maximum 7 children now");
          }
      }
docs: {@inheritDoc}
  <p/>
  Currently, this layout supports maximum children up to 5, otherwise {@link
  IllegalArgumentException}
  will be thrown
  
  @param start start position of items handled by this layoutHelper
  @param end   end position of items handled by this layoutHelper, if end &lt; start or end -
  start &gt 4, it will throw {@link IllegalArgumentException}