NameError: name 'PlainBufferGeometry' is not defined in jupyter notebook on pythreejs in chrome

I have this codes in jupyter notebook on pythreejs in chrome:

the github address: https://github.com/jovyan/pythreejs/blob/master/examples/Examples.ipynb

the source said : Buffer Geometries The PlainBufferGeometry object uses several tricks to speed up both the transfer of data and the rendering of the data.

from pythreejs import *
import numpy as np
from IPython.display import display

vertices = np.asarray([
[0, 0, 0],
[0, 0, 1],
[0, 1, 0],
[0, 1, 1],
[1, 0, 0],
[1, 0, 1],
[1, 1, 0],
[1, 1, 1]
], dtype='float32')

faces = np.asarray([
        [0, 1, 3],
        [0, 2, 3],
        [0, 2, 4],
        [2, 4, 6],
        [0, 1, 4],
        [1, 4, 5],
        [2, 3, 6],
        [3, 6, 7],
        [1, 3, 5],
        [3, 5, 7],
        [4, 5, 6],
        [5, 6, 7]
    ])

vertexcolors = np.asarray([(0,0,0), (0,0,1), (0,1,0), (1,0,0), (0,1,1), (1,0,1), (1,1,0), (1,1,1)])

cubeGeometry = PlainBufferGeometry(vertices=vertices, faces=faces, colors = vertexcolors)

myobjectCube = Mesh(geometry=cubeGeometry, material = LambertMaterial(vertexColors = 'VertexColors'))
cCube = PerspectiveCamera(position=[3, 3, 3], fov=20,
                      children=[DirectionalLight(color='#ffffff', position=[-3, 5, 1], intensity=0.5)])
sceneCube = Scene(children=[myobjectCube, AmbientLight(color='#dddddd')])

rendererCube = Renderer(camera=cCube, background='black', background_opacity=1,
                        scene = sceneCube, controls=[OrbitControls(controlling=cCube)])

display(rendererCube)

but when running I got this error:

NameError                                 Traceback (most recent call last)
<ipython-input-14-f2777808a126> in <module>()
     31 vertexcolors = np.asarray([(0,0,0), (0,0,1), (0,1,0), (1,0,0), (0,1,1), (1,0,1), (1,1,0), (1,1,1)])
     32 
---> 33 cubeGeometry = PlainBufferGeometry(vertices=vertices, faces=faces, colors = vertexcolors)
     34 
     35 myobjectCube = Mesh(geometry=cubeGeometry, material = LambertMaterial(vertexColors = 'VertexColors'))

NameError: name 'PlainBufferGeometry' is not defined

so what should I do? best regards

via hasanbaghal