human
I wrote the below code

    def contains(seq, x):
        for item in seq:
            if (item is x):
                return True
            elif (item.is_sequence_constructor and contains(item.args, x)):
                return True
        return False
    def lower_than(a, b):
        return (b.is_sequence_constructor and contains(b.args, a))
    for (pos, item) in enumerate(items):
        key = item[1]
        new_pos = pos
        for i in range((pos - 1), (-1), (-1)):
            if lower_than(key, items[i][0]):
                new_pos = i
        if (new_pos != pos):
            for i in range(pos, new_pos, (-1)):
                items[i] = items[(i - 1)]
            items[new_pos] = item

What's a good function header?
assistant
#Here's a good function header.

def sort_common_subsequences(items):