human
I wrote the below code

    path_list = path_list[:]
    new_path_list = []
    for (ii, (path, is_unsav)) in enumerate(zip(path_list, is_unsaved)):
        if is_unsav:
            new_path_list.append(_('unsaved    file'))
            path_list[ii] = None
        else:
            (drive, path) = osp.splitdrive(osp.dirname(path))
            new_path_list.append((drive + osp.sep))
            path_list[ii] = [part for part in path.split(osp.sep) if part]
    def recurse_level(level_idx):
        sep = os.sep
        if (not any(level_idx.values())):
            return
        sample_toks = list(level_idx.values())[0]
        if (not sample_toks):
            s = 0
        else:
            for (s, sample_val) in enumerate(sample_toks):
                if (not all((((len(toks) > s) and (toks[s] == sample_val)) for toks in level_idx.values()))):
                    break
        if (s == 0):
            short_form = ''
        else:
            if (s == 1):
                short_form = sample_toks[0]
            elif (s == 2):
                short_form = ((sample_toks[0] + sep) + sample_toks[1])
            else:
                short_form = (('...' + sep) + sample_toks[(s - 1)])
            for idx in level_idx:
                new_path_list[idx] += (short_form + sep)
                level_idx[idx] = level_idx[idx][s:]
        while level_idx:
            (k, group) = (0, level_idx)
            while True:
                prospective_group = {idx: toks for (idx, toks) in group.items() if (len(toks) == k)}
                if prospective_group:
                    if (k == 0):
                        group = prospective_group
                    break
                (_, sample_toks) = next(iteritems(group))
                prospective_group = {idx: toks for (idx, toks) in group.items() if (toks[k] == sample_toks[k])}
                if ((len(prospective_group) == len(group)) or (k == 0)):
                    group = prospective_group
                    k += 1
                else:
                    break
            (_,...

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

def shorten_paths(path_list, is_unsaved):