docs: private void feedForward(Vec input, List<Vec> activations, List<Vec> derivatives)
      {
          Vec x = input;
          for(int i = 0; i < Ws.size(); i++)
          {
              Matrix W_i = Ws.get(i);
              Vec b_i = bs.get(i);
  
              Vec a_i = activations.get(i);
              a_i.zeroOut();
              W_i.multiply(x, 1, a_i);
              a_i.mutableAdd(b_i);
              
              a_i.applyFunction(f);
              
              Vec d_i = derivatives.get(i);
              a_i.copyTo(d_i);
              d_i.applyFunction(f.getD());
              
              x = a_i;
          }
      }