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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 max_interval_intersec(S):
 """determine a value that is contained in a largest number of given intervals :param S: list of half open intervals :complexity: O(n log n), where n = len(S) """

    B = ([(left,  +1) for left, right in S] +
         [(right, -1) for left, right in S])
    B.sort()
    c = 0
    best = (c, None)
    for x, d in B:
        c += d
        if best[0] < c:
            best = (c, x)
    return best