Button Connect Signal problem inside Class

Question

I am new to GDScript and a bit newbie type in programming.....I am Trying to implement button connect signal action inside user-defined class....but its not working.....is there any other way to implement the button pressed action or any other way out

Here is simplified version of the code I am using

 

extends Node

class example :

    var a=2

    var b=6

    var c

    var button

func add_button(handle,text:String) :
    Button_click() # working
    button=Button.new()
    button.text=text
    button.connect("pressed",self,"Button_click") # Not working
    handle.add_child(button)

func Button_click():
    c=a+b
    print("C="+str(c))

func _ready():  
    var My_Class=example.new()
    My_Class.add_button(self,"Click to see C")