docs: public SDVariable reductionBroadcastableWithOrigShape(int origRank, int[] reduceDims, SDVariable toExpand) {
          if (Shape.isWholeArray(origRank, reduceDims)) {
              //Output is [1,1] which is already broadcastable
              return toExpand;
          } else if (origRank == 2 && reduceDims.length == 1) {
              //In this case: [a,b] -> [1,b] or [a,b] -> [a,1]
              //both are already broadcastable
              return toExpand;
          } else {
              //Example: [a,b,c].sum(1) -> [a,c]... want [a,1,c]
              for (int d : reduceDims) {
                  toExpand = sameDiff().expandDims(toExpand, d);
              }
              return toExpand;
          }
      }