code: public void getAllUpstreamElements( List<IHillSlope> elems, List<PfafstetterNumber> limit ) {
          // if the limit is the number of the actual element, return
          if (limit != null && limit.size() > 0) {
              for( PfafstetterNumber pfafs : limit ) {
                  if (pfafs.compareTo(pfafstetterNumber) == 0) {
                      return;
                  }
              }
          }
          elems.add(this);
          for( IHillSlope upstreamElement : upstreamElements ) {
              upstreamElement.getAllUpstreamElements(elems, limit);
          }
      }
docs: /* (non-Javadoc)
  @see org.hortonmachine.hmachine.modules.hydrogeomorphology.adige.core.IHillSlope#getAllUpstreamElements(java.util.List, java.util.List)