def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def _split_vertical(container):
		r1 = None
		r2 = None
		min_w = int(W_RATIO*container.h)+1
		if container.w < 2*min_w:
			return None
		r1 = Container(container.x,container.y,randint(min_w, container.w-min_w),container.h)
		r2 = Container(container.x+r1.w,container.y,container.w-r1.w,container.h)
		return [r1, r2]