code: @Override
      @SuppressWarnings("unchecked")
      public void backward() {
          T xAdj = modIn.getOutputAdj();
          T tmp = (T) yAdj.copyAndConvertAlgebra(modIn.getAlgebra());
          xAdj.elemAdd(tmp);
      }
docs: Backward pass: dG/dx_i = dG/dy_i.
  dG/dy_i is converted to a real from the semiring form.