Process a function on class instance when variable hosting this objet is reassigned

Question

I would how activating a function to clean all my reference of this object in other structure when his variable is reassigned (so the object should be unreferenced everywhere )

rvc =ReferenceValueCluster()
rvc('key1')

wk = WeakrefDict(refval=rvc)
wk['key1'] =rvc('value1','value')
wk = WeakrefDict()

in this case wk is reassigned to a new WeakrefDict, I looking for a way to unreferencing this object everywhere.

I tried to figure it out with garbage collection and a custom call back at the start but gc is not activated after reassigned variable

import gc
import sys
class test():
    def __init__(self) -> None:
        self.text = "tejkejkej"
        self.list = []
        self.list.append(self)

    def __del__(self)->None:
        print('del test')

class test2():
    def __init__(self) -> None:
        self.list =[]

import copy

import inspect


def retrieve_name(var):
    for fi in reversed(inspect.stack()):
        names = [var_name for var_name, var_val in fi.frame.f_locals.items() if var_val is var]
        if len(names) > 0:
            return names[0]
a =test()
b = a
w = test2()

w.list.append(a)
c = sys.getrefcount(a)
del c
l = dict()


def gb_callback_example(phase, info):
    print(phase)
    print(info["collected"])
    if phase =='start':
        temp = gc.get_referrers(a)[-1]
        dic = copy.copy(temp)
        print('-----------')
        for k, v in dic.items():
            print(retrieve_name(k))
            print(retrieve_name(a))
            print('----(((')
            if type(v) == test and k != retrieve_name(a):
                 l[k] = v
        print(l)  

 gc.callbacks.append(gb_callback_example)

a=0
w =[1,2,3]

when the variable a is reassigned to 0value , garbage collection is not activated