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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def powerstring_by_border(u):
 """Power string by Knuth-Morris-Pratt :param x: string :returns: largest k such that there is a string y with x = y^k :complexity: O(len(x)) """

    f = maximum_border_length(u)
    n = len(u)
    if n % (n - f[-1]) == 0:       # does the alignment shift divide n ?
        return n // (n - f[-1])    # we found a power decomposition
    return 1