Godot_bridge/addon/menus/__init__.py

from .panel_main import KH_PT_panel_main

classes = (
    KH_PT_panel_main,
)

def register_menus():
    from bpy.utils import register_class
    for cls in classes:
        register_class(cls)

def unregister_menus():
    from bpy.utils import unregister_class
    for cls in classes:
        unregister_class(cls)