docs: private Vec feedForward(Vec input)
      {
          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 = W_i.multiply(x);
              a_i.mutableAdd(b_i);
              
              a_i.applyFunction(f);
              
              x = a_i;
          }
          
          return x;
      }