human
Solve the following python programming problem given the following code:
def testTaskInstance2(self) : 
    AdderInstance = TaskInstance (True) 
    with AdderInstance.set (Adder (10)) : 
        self.assertEquals (30, AdderInstance.sum (20)) 
        def t() : 
            self.assertEquals (30, AdderInstance.sum (20)) 
            with AdderInstance.set (Adder (20)) : 
                self.assertEquals (40, AdderInstance.sum (20)) 
self.assertEquals (30, AdderInstance.sum (20)) 
t1 = Tasklet.new (t) () 
        t2 = Tasklet.new (t) () 
        Tasklet.join_all ([self, t2]) 
        self.assertEquals (30, AdderInstance.sum (20)) 

    
    

    Fix the buggy line: Tasklet.join_all ([self, t2])
assistant
#Here is Python program to fix the buggy line: Tasklet.

Tasklet.join_all ([t1, t2])