def interval_set_to_set(intervals):
    """ Convert interval set to python set

    >>> interval_set_to_set([])
    set()
    >>> interval_set_to_set([(1, 1), (3, 4)])
    {1, 3, 4}
    """
    s = set()
    for begin, end in intervals:
        for x in range(begin, end + 1):
            s.add(x)
    return s
