The function’s documentation string (Jupyter) is not working when I use methods of a class into the second class

[abolfazldelavar]

Dear all,
I have a class in Jupyter (in VS Code) named a including another class as a method named b. In the b class, there is a function named c. Now, when I want to use that in Jupyter, I will have to write a.b.c() to have access to that. In Jupyter, usually when we hover the name of any functions, the navigator of VS Code shows us the instruction of the function. Note that I have some instruction for the function c.
However, when I hover the name of c in the a.b.c(), nothing will happen. In other words, I guess the VB Code Jupyter can not detect that function to pop up its documentation immediately.

It is worth mentioning that the code can be run without any problem and the only problem I have is with the hover action which I need to have the functions documentations immediately. I have this issue when I use class into the other class like a.b.c() and there is no problem in showing the documentation for a function in only one class like a.d() as long as d is a function in a class. In other words, when I hover d in the expression a.d(), every thing is OK and the documentation of d will be shown, while it does not work for c when I hover it in a.b.c(). Note that it happens especially when I write the whole code in different parts in a Jupyter file, not just in a chunk of code continually.

Let me share the piece of code to elaborate more:

class bb():
    def __init__(self, x):
        self.loop = x
    def c(self):
        '''
        This is the documentation of c function
        '''
        return self.loop

class aa():
    def __init__(self):
        pass
    def d(self):
        '''
        This is the documentation of d function
        '''
        return 'Hello'

a = aa
a.b = bb(5)

a.b.c
a.d

The below images shows the consequence of what I have just shared with you. As it is clear, c are unknown for jupyter. why?!
how can I fix it?

[abolfazldelavar]

Dear all,
Ehat should I do for this problem?