module 'open3d.open3d.visualization' has no attribute '__DEVICE_API__'

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

i run the example code,but got error!
`o3d.__version__ ` is '0.7.0.0'
```python
# ----------------------------------------------------------------------------
# - Open3D: www.open3d.org -
# ----------------------------------------------------------------------------
# The MIT License (MIT)
#
# Copyright (c) 2018-2021 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 open3d.visualization.gui as gui
import open3d.visualization.rendering as rendering
import platform
import random
import threading
import time

isMacOS = (platform.system() == "Darwin")

# This example shows two methods of adding geometry to an existing scene.
# 1) add via a UI callback (in this case a menu, but a button would be similar,
# you would call `button.set_on_clicked(self.on_menu_sphere_)` when
# configuring the button. See `on_menu_sphere()`.
# 2) add asynchronously by polling from another thread. GUI functions must be
# called from the UI thread, so use Application.post_to_main_thread().
# See `on_menu_random()`.
# Running the example will show a simple window with a Debug menu item with the
# two different options. The second method will add random spheres for
# 20 seconds, during which time you can be interacting with the scene, rotating,
# etc.
class SpheresApp:
MENU_SPHERE = 1
MENU_RANDOM = 2
MENU_QUIT = 3

def __init__(self):
self._id = 0
self.window = gui.Application.instance.create_window(
"Add Spheres Example", 1024, 768)
self.scene = gui.SceneWidget()
self.scene.scene = rendering.Open3DScene(self.window.renderer)
self.scene.scene.set_background([1, 1, 1, 1])
self.scene.scene.scene.set_sun_light(
[-1, -1, -1], # direction
[1, 1, 1], # color
100000) # intensity
self.scene.scene.scene.enable_sun_light(True)
bbox = o3d.geometry.AxisAlignedBoundingBox([-10, -10, -10],
[10, 10, 10])
self.scene.setup_camera(60, bbox, [0, 0, 0])

self.window.add_child(self.scene)

# The menu is global (because the macOS menu is global), so only create
# it once, no matter how many windows are created
if gui.Application.instance.menubar is None:
if isMacOS:
app_menu = gui.Menu()
app_menu.add_item("Quit", SpheresApp.MENU_QUIT)
debug_menu = gui.Menu()
debug_menu.add_item("Add Sphere", SpheresApp.MENU_SPHERE)
debug_menu.add_item("Add Random Spheres", SpheresApp.MENU_RANDOM)
if not isMacOS:
debug_menu.add_separator()
debug_menu.add_item("Quit", SpheresApp.MENU_QUIT)

menu = gui.Menu()
if isMacOS:
# macOS will name the first menu item for the running application
# (in our case, probably "Python"), regardless of what we call
# it. This is the application menu, and it is where the
# About..., Preferences..., and Quit menu items typically go.
menu.add_menu("Example", app_menu)
menu.add_menu("Debug", debug_menu)
else:
menu.add_menu("Debug", debug_menu)
gui.Application.instance.menubar = menu

# The menubar is global, but we need to connect the menu items to the
# window, so that the window can call the appropriate function when the
# menu item is activated.
self.window.set_on_menu_item_activated(SpheresApp.MENU_SPHERE,
self._on_menu_sphere)
self.window.set_on_menu_item_activated(SpheresApp.MENU_RANDOM,
self._on_menu_random)
self.window.set_on_menu_item_activated(SpheresApp.MENU_QUIT,
self._on_menu_quit)

def add_sphere(self):
self._id += 1
mat = rendering.MaterialRecord()
mat.base_color = [
random.random(),
random.random(),
random.random(), 1.0
]
mat.shader = "defaultLit"
sphere = o3d.geometry.TriangleMesh.create_sphere(0.5)
sphere.compute_vertex_normals()
sphere.translate([
10.0 * random.uniform(-1.0, 1.0), 10.0 * random.uniform(-1.0, 1.0),
10.0 * random.uniform(-1.0, 1.0)
])
self.scene.scene.add_geometry("sphere" + str(self._id), sphere, mat)

def _on_menu_sphere(self):
# GUI callbacks happen on the main thread, so we can do everything
# normally here.
self.add_sphere()

def _on_menu_random(self):
# This adds spheres asynchronously. This pattern is useful if you have
# data coming in from another source than user interaction.
def thread_main():
for _ in range(0, 20):
# We can only modify GUI objects on the main thread, so we
# need to post the function to call to the main thread.
gui.Application.instance.post_to_main_thread(
self.window, self.add_sphere)
time.sleep(1)

threading.Thread(target=thread_main).start()

def _on_menu_quit(self):
gui.Application.instance.quit()

def main():
gui.Application.instance.initialize()
SpheresApp()
gui.Application.instance.run()

if __name__ == "__main__":
main()
```
```
Exception has occurred: AttributeError
module 'open3d.open3d.visualization' has no attribute '__DEVICE_API__'
File "/home/kouguozhao/Documents/kouguozhao/motion planning/CoMPNetX/test.py", line 28, in
import open3d.visualization.gui as gui
```