Gets the set of most common states among the state sets contained in the iterable argument
    :param state_iterable: iterable of state sets
    :return: set of most common states

def get_most_common_states(state_iterable):
    """
    Gets the set of most common states among the state sets contained in the iterable argument
    :param state_iterable: iterable of state sets
    :return: set of most common states
    """
    state_counter = Counter()
    for states in state_iterable:
        state_counter.update(states)
    max_count = state_counter.most_common(1)[0][1]
    return {state for (state, count) in state_counter.items() if count == max_count}