if I want these classes to be called by other plugins, like Pie Menu Editor addon, What code should I add？

[![enter image description here][1]][1]
```
import bpy

class Cam_Base(bpy.types.Operator):
    bl_idname = "cam.base"
    bl_label = "Cam Base"
    cam_name = "C_"
    
    def execute(self, context):
        C = bpy.context

        # lock cam
        bpy.context.object.lock_scale = (True, True, True)
        bpy.context.object.lock_rotation = (True, True, True)
        bpy.context.object.lock_location = (True, True, True)

        # select cam
        bpy.context.space_data.camera = bpy.data.objects[self.cam_name]

        # Select Active Cam
        for area in C.screen.areas:
            if area.type == 'VIEW_3D':
                A = C.area.spaces.active.camera

        bpy.context.scene.camera = bpy.data.objects[A.name]
        return {'FINISHED'}

class Cam_0V0(Cam_Base):
    bl_idname = "cam.0v0"
    bl_label = "Cam_0V0"
    cam_name = "C_0V0"

class Cam_0V1(Cam_Base):
    bl_idname = "cam.0v1"
    bl_label = "Cam_0V1"
    cam_name = "C_0V1"

class Cam_0V2(Cam_Base):
    bl_idname = "cam.0v2"
    bl_label = "Cam_0V2"
    cam_name = "C_0V2"

addon_keymaps = []

def register():
    bpy.utils.register_class(Cam_Base)
    bpy.utils.register_class(Cam_0V0)
    bpy.utils.register_class(Cam_0V1)
    bpy.utils.register_class(Cam_0V2)

def unregister():
    bpy.utils.unregister_class(Cam_Base)
    bpy.utils.unregister_class(Cam_0V0)
    bpy.utils.unregister_class(Cam_0V1)
    bpy.utils.unregister_class(Cam_0V2)

if __name__ == "__main__":
    register()
```


  [1]: https://i.sstatic.net/AHdwt.png