code: @Override
      public VarTensor forward() {
          VarTensor x = modInX.getOutput();
          y = new VarTensor(s, x.getVars());
          for (int c = 0; c < y.size(); c++) {
              y.setValue(c, s.fromLogProb(x.getValue(c)));
          }
          return y;
      }
docs: Foward pass: y_i = exp(x_i)