text: import torch
  from torch.autograd import Variable
  def f(x):
      y = x ** 2 -3
      return y
  x = Variable(torch.Tensor([15]), requires_grad=True)
  for i in range(40):
      grad_x = torch.autograd.grad(f(x), x, create_graph=True)
      grad_grad_x = torch.autograd.grad(grad_x[0], x)
      x = Variable(x.data - grad_x[0].data / grad_grad_x[0].data, requires_grad=True)
  print(x)
  