код:

from ursina import *


class Game(Ursina):
def __init__(self):
    super().__init__()
    window.fullscreen = True
    Entity(model="quad", scale=60, texture="white_cube", texture_scale=(60, 60), 
 rotation_x=90, y=-5,
           color=color.light_gray)  # plane
    Entity(model="sphere", scale=100, texture="textures/sky0", double_sided=True)  # sky
    EditorCamera()
    camera.world_position = (0, 0, -15)
    self.model, self.texture="models/custom_cube", 'textures/rubik_texture'
    self.load_game()

def load_game(self):
    self.create_cube_positions()
    self.CUBES = [Entity(model=self.model, texture=self.texture, position=pos) for pos in self.SIDE_POSITIONS]
    self.PARENT = Entity()
    self.rotation_axes = {'LEFT': 'x', 'RIGHT': 'x', 'TOP': 'y', 'BOTTOM': 'y', 'FACE': 'z', 'BACK': 'z'}
    self.cubes_side_positons = {'LEFT': self.LEFT, 'BOTTOM': self.BOTTOM, 'RIGHT': self.RIGHT, 'FACE': self.FACE,
                                'BACK': self.BACK, 'TOP': self.TOP}
    self.animation_time = 0.5
    self.action_trigger = True
    self.action_mode = True
    self.message = Text(origin=(0, 19), color=color.black)
    self.toggle_game_mode()
    self.create_sensors()
    self.random_state(rotations=3) # initial state of the cube, rotations - number of side turns

def random_state(self, rotations=3):
    [self.rotate_side_without_animation(random.choice(list(self.rotation_axes))) for i in range(rotations)]

def rotate_side_without_animation(self, side_name):
    cube_positions = self.cubes_side_positons[side_name]
    rotation_axis = self.rotation_axes[side_name]
    self.reparent_to_scene()
    for cube in self.CUBES:
        if cube.position in cube_positions:
            cube.parent = self.PARENT
            exec(f'self.PARENT.rotation_{rotation_axis} = 90')

def create_sensors(self):
    '''detectors for each side, for detecting collisions with mouse clicks'''
    create_sensor = lambda name, pos, scale: Entity(name=name, position=pos, model="cube", color=color.dark_gray,
                                                    scale=scale, collider="box", visible=False)
    self.LEFT_sensor = create_sensor(name="LEFT", pos=(-0.99, 0, 0), scale=(1.01, 3.01, 3.01))
    self.FACE_sensor = create_sensor(name="FACE", pos=(0, 0, -0.99), scale=(3.01, 3.01, 1.01))
    self.BACK_sensor = create_sensor(name="BACK", pos=(0, 0, 0.99), scale=(3.01, 3.01, 1.01))
    self.RIGHT_sensor = create_sensor(name="RIGHT", pos=(0.99, 0, 0), scale=(1.01, 3.01, 3.01))
    self.TOP_sensor = create_sensor(name="TOP", pos=(0, 1, 0), scale=(3.01, 1.01, 3.01))
    self.BOTTOM_sensor = create_sensor(name="BOTTOM", pos=(0, -1, 0), scale=(3.01, 1.01, 3.01))

def toggle_game_mode(self):
    '''switching view mode or interacting with Rubik's cube'''
    self.action_mode = not self.action_mode
    msg = dedent(f"{'ACTION mode ON' if self.action_mode else 'VIEW mode ON'}"
                 f" (to switch - press middle mouse button)").strip()
    self.message.text = msg

def toggle_animation_trigger(self):
    '''prohibiting side rotation during rotation animation'''
    self.action_trigger = not self.action_trigger

def rotate_side(self, side_name):
    self.action_trigger = False
    cube_positions = self.cubes_side_positons[side_name]
    rotation_axis = self.rotation_axes[side_name]
    self.reparent_to_scene()
    for cube in self.CUBES:
        if cube.position in cube_positions:
            cube.parent = self.PARENT
            eval(f'self.PARENT.animate_rotation_{rotation_axis}(90, duration=self.animation_time)')
    invoke(self.toggle_animation_trigger, delay=self.animation_time + 0.11)

def reparent_to_scene(self):
    for cube in self.CUBES:
        if cube.parent == self.PARENT:
            world_pos, world_rot = round(cube.world_position, 1), cube.world_rotation
            cube.parent = scene
            cube.position, cube.rotation = world_pos, world_rot
    self.PARENT.rotation = 0

def create_cube_positions(self):
    self.LEFT = {Vec3(-1, y, z) for y in range(-1, 2) for z in range(-1, 2)}
    self.BOTTOM = {Vec3(x, -1, z) for x in range(-1, 2) for z in range(-1, 2)}
    self.FACE = {Vec3(x, y, -1) for x in range(-1, 2) for y in range(-1, 2)}
    self.BACK = {Vec3(x, y, 1) for x in range(-1, 2) for y in range(-1, 2)}
    self.RIGHT = {Vec3(1, y, z) for y in range(-1, 2) for z in range(-1, 2)}
    self.TOP = {Vec3(x, 1, z) for x in range(-1, 2) for z in range(-1, 2)}
    self.SIDE_POSITIONS = self.LEFT | self.BOTTOM | self.FACE | self.BACK | self.RIGHT | self.TOP

def input(self, key):
    if key in 'mouse1 mouse3' and self.action_mode and self.action_trigger:
        for hitinfo in mouse.collisions:
            collider_name = hitinfo.entity.name
            if (key == 'mouse1' and collider_name in 'LEFT RIGHT FACE BACK' or
                    key == 'mouse3' and collider_name in 'TOP BOTTOM'):
                self.rotate_side(collider_name)
                break
    if key == 'mouse2':
        self.toggle_game_mode()
    super().input(key)


if __name__ == '__main__':
    game = Game()
    game.run()

ошибка:

Traceback (most recent call last):
  File "C:\Users\Admin\PycharmProjects\Rubiks-Cube-3D\main.py", line 4, in <module>
    class Game(Ursina):
TypeError: function() argument 'code' must be code, not str