human
Solve the following python programming problem given the following code:
@ tz.memoize 
def _build_spread_kernel(how) : 
    'Build a spreading kernel for a given composite operator' 
    op = composite_op_lookup [op] 
    @ ngjit 
    def kernel(arr, mask, out) : 
        (M, N) = arr.shape 
        w = mask.shape [0] 
        for y in range (M) : 
            for x in range (N) : 
                el = arr [(y, x)] 
                if ((el >> 24) & 255) : 
                    for i in range (w) : 
                        for j in range (w) : 
                            if mask [(i, j)] : 
                                out [((i + y), (j + x))] = op (el, out [((i + y), (j + x))]) 
return kernel 

    
    

    Fix the buggy line: op = composite_op_lookup [op]
assistant
#Here is Python code to fix the buggy line: op = composite_op_lookup [op]
.

op = composite_op_lookup [how]