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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 interval_cover(I):
 """Minimum interval cover :param I: list of closed intervals :returns: minimum list of points covering all intervals :complexity: O(n log n) """

    S = []
    for start, end in sorted(I, key=lambda v: v[1]):
        if not S or S[-1] < start:
            S.append(end)
    return S