text: # ----------------------------------------------------------------------------
  # -                        Open3D: www.open3d.org                            -
  # ----------------------------------------------------------------------------
  # The MIT License (MIT)
  #
  # Copyright (c) 2020 www.open3d.org
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  # IN THE SOFTWARE.
  # ----------------------------------------------------------------------------
  
  import open3d as o3d
  import numpy as np
  import pytest
  
  import open3d as o3d
  import numpy as np
  import pytest
  
  
  def torch_available():
      try:
          import torch
          import torch.utils.dlpack
      except ImportError:
          return False
      return True
  
  
  def list_devices():
      """
      If Open3D is built with CUDA support:
      - If cuda device is available, returns [Device("CPU:0"), Device("CUDA:0")].
      - If cuda device is not available, returns [Device("CPU:0")].
  
      If Open3D is built without CUDA support:
      - returns [Device("CPU:0")].
      """
      devices = [o3d.core.Device("CPU:" + str(0))]
      if torch_available() and o3d._build_config['BUILD_CUDA_MODULE']:
          import torch
          import torch.utils.dlpack
          if (o3d.core.cuda.device_count() != torch.cuda.device_count()):
              raise RuntimeError(
                  "o3d.core.cuda.device_count() != torch.cuda.device_count(), "
                  "{} != {}".format(o3d.core.cuda.device_count(),
                                    torch.cuda.device_count()))
      if o3d.core.cuda.device_count() > 0:
          devices.append(o3d.core.Device("CUDA:0"))
      return devices
  