manipulate python variable inside a GTK action listener

I'm trying to an action listener that is attached to a checkbox button. My goal is to toggle the variable value ( 0 or 1 ) whenever the checkbox is checked/unchecked.

I come from a C background and am fairly new to python. I've also been reading up on global variable but I cannot seem to grasp it.

I will do an example in C first :

//#includes

int test; //i could say public int test but it is public by default

int foo()
{
    test = 1;
    return test;
}
void main()
{
   test = 0;
   print (foo);
}

Some example python code is below.

class someRandomClass: 

    def on_checkbutton1_toggled(self, widget, data=None):
        if test == 0:
            test = 1
        if test == 1:
            test = 0

    def __init__(self):
        global test
        test = 0

if __name__ == "__main__":
    main = someRandomClass()
    gtk.main()

Executing this python code and clicking on the checkbox throws an UnboundLocalError: local variable 'test' referenced before assignment

I've tried creating the global variable outside of a function but still inside the class - the same method as the example C code.