code: private Map<String, Integer> getTranscriptionalControls(
              Collection<KamEdge> edges) {
          Map<String, Integer> controlCountMap = new HashMap<String, Integer>();
          for (KamEdge edge : edges) {
              if (edge.getTargetNode().getFunctionType() == FunctionEnum.RNA_ABUNDANCE
                      && isCausal(edge)) {
                  if (controlCountMap
                          .containsKey(edge.getSourceNode().getLabel())) {
                      int count =
                              controlCountMap
                                      .get(edge.getSourceNode().getLabel());
                      count = count + 1;
                      controlCountMap.put(edge.getSourceNode().getLabel(), count);
                  } else {
                      controlCountMap.put(edge.getSourceNode().getLabel(), 1);
                  }
              }
          }
  
          return controlCountMap;
      }
docs: returns nodes with causal downstream to rnaAbundance() nodes.
  @param edges
  @return