docs: public static Info kron( final Variable A , final Variable B, ManagerTempVariables manager) {
          Info ret = new Info();
          final VariableMatrix output = manager.createMatrix();
          ret.output = output;
  
          if( A instanceof VariableMatrix && B instanceof VariableMatrix ) {
              ret.op = new Operation("kron-mm") {
                  @Override
                  public void process() {
                      DMatrixRMaj mA = ((VariableMatrix)A).matrix;
                      DMatrixRMaj mB = ((VariableMatrix)B).matrix;
                      output.matrix.reshape(mA.numRows * mB.numRows, mA.numCols * mB.numCols);
                      CommonOps_DDRM.kron(mA, mB, output.matrix);
                  }
              };
          } else {
              throw new RuntimeException("Both inputs must be matrices ");
          }
  
          return ret;
      }