def append_base(trimmed_tour, base_city):
    """
    Appends a common start/end to a tour
    E.g. when passed
    trimmed_tour = [1,2]
    base_city = 0
    The func returns [0, 1, 2, 0]
    """
    trimmed_tour.append(base_city)
    trimmed_tour.insert(0, base_city)
    return trimmed_tour