you need to delete or comment completely

I mean you need delete or comment the `@classmethod`  too

    import bpy
    
    class MonkeyOperator(bpy.types.Operator):
        """Tooltip"""
        bl_idname = "object.make_monkey"
        bl_label = "Monkey Operator"
    
        
        
    
        def execute(self, context):
            main(context)
            return {'FINISHED'}
    
    
    def register():
        bpy.utils.register_class(MonkeyOperator)
    
    
    def unregister():
        bpy.utils.unregister_class(MonkeyOperator)
    
    
    if __name__ == "__main__":
        register()