code: def test_IdentityVectorFunction():
      x0 = np.zeros(3)
  
      f1 = IdentityVectorFunction(x0, None)
      f2 = IdentityVectorFunction(x0, False)
      f3 = IdentityVectorFunction(x0, True)
  
      assert_(f1.sparse_jacobian)
      assert_(not f2.sparse_jacobian)
      assert_(f3.sparse_jacobian)
  
      x = np.array([-1, 2, 1])
      v = np.array([-2, 3, 0])
  
      assert_array_equal(f1.fun(x), x)
      assert_array_equal(f2.fun(x), x)
  
      assert_array_equal(f1.jac(x).toarray(), np.eye(3))
      assert_array_equal(f2.jac(x), np.eye(3))
  
      assert_array_equal(f1.hess(x, v).toarray(), np.zeros((3, 3)))
  
imports: import pytest
  import numpy
  from numpy.testing import TestCase, assert_array_almost_equal, assert_array_equal, assert_, assert_allclose, assert_equal
  from scipy.sparse import csr_matrix
  from scipy.sparse.linalg import LinearOperator
  from scipy.optimize._differentiable_functions import ScalarFunction, VectorFunction, LinearVectorFunction, IdentityVectorFunction
  from scipy.optimize._hessian_update_strategy import BFGS
label_desc: Use image node_id 3 for calling a global function with example usage: test_IdentityVectorFunction() without return types