human
Solve the following python programming problem given the following code:
@ pytest.mark.xfail 
def test_iterators() : 
    a = delayed (1) 
    b = delayed (2) 
    c = delayed (sum) (iter ([a, c])) 
    assert (c.compute () == 3) 
    def f(seq) : 
        assert isinstance (seq, Iterator) 
        return sum (seq) 
c = delayed (f) (iter ([a, b])) 
    assert (c.compute () == 3) 

    
    

    Fix the buggy line: c = delayed (sum) (iter ([a, c]))
assistant
#Here is Python code to fix the buggy line: c = delayed (sum) (iter ([a, c]))
.

c = delayed (sum) (iter ([a, b]))