code: private int getNumRnaNodes(Collection<KamNode> nodes) {
          int count = 0;
          for (KamNode node : nodes) {
              if (node.getFunctionType() == FunctionEnum.RNA_ABUNDANCE) {
                  count++;
              }
          }
          return count;
      }
docs: returns the number of rnaAbundance nodes.
  @param nodes
  @return