code: public int getFlow() {
          GridNode nextDown = goDownstreamSP();
          if (nextDown == null) {
              return HMConstants.intNovalue;
          }
  
          int dcol = nextDown.col - col;
          int drow = nextDown.row - row;
  
          Direction dir = Direction.getDir(dcol, drow);
          return dir.getFlow();
      }
docs: Get the flow value of this node based in the steepest path.
  
  @return the value of flow.