code: def test_hessian_mvn():
      tmp = torch.randn(3, 10)
      cov = torch.matmul(tmp, tmp.t())
      mvn = dist.MultivariateNormal(cov.new_zeros(3), cov)
  
      x = torch.randn(3, requires_grad=True)
      y = mvn.log_prob(x)
      assert_equal(hessian(y, x), -mvn.precision_matrix)
  
imports: import torch
  import pyro.distributions
  from pyro.ops.hessian import hessian
  from tests.common import assert_equal
label_desc: Use image node_id 1 for calling a global function with example usage: test_hessian_mvn() without return types