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Given the following text description, write Python code to implement the functionality described.
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Description:
This function takes a list l and returns a list l' such that
    l' is identical to l in the indicies that are not divisible by three, while its values at the indicies that are divisible by three are equal
    to the values of the corresponding indicies of l, but sorted.
    
This is how the function will work:
 sort_third([1, 2, 3])
    [1, 2, 3]
    
This is how the function will work:
 sort_third([5, 6, 3, 4, 8, 9, 2])
    [2, 6, 3, 4, 8, 9, 5]
    
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Python Code:
def sort_third(l: list):
    
    l = list(l)
    l[::3] = sorted(l[::3])
    return l
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