class_docstr: Most tests done in the base class LinearOperatorDerivedClassTest.
docstr: We overwrite the FFT operation mapping for testing.
docstr_tok: ["We","overwrite","the","FFT","operation","mapping","for","testing","."]
code: def _constrain_devices_and_set_default(
      self, sess, use_gpu, force_gpu
  ):
      """We overwrite the FFT operation mapping for testing."""
      with test.TestCase._constrain_devices_and_set_default(
          self, sess, use_gpu, force_gpu
      ) as sess:
          yield sess
  
imports: import contextlib
  import numpy
  import scipy.linalg
  from tensorflow.python.eager import backprop
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.ops.linalg import linalg
  from tensorflow.python.ops.linalg import linear_operator_test_util
  from tensorflow.python.ops.linalg import linear_operator_toeplitz
  from tensorflow.python.platform import test
label_desc: Use image node_id 1 for calling the LinearOperatorToeplitzTest obj's underlying member method code with example usage: obj._constrain_devices_and_set_default(sess, use_gpu, force_gpu) without return types