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 image_url(self, pixel_size=None):
        """
        Get the URL for the user icon in the desired pixel size, if it exists. If no
        size is supplied, give the URL for the full-size image.
        """
        if "profile" not in self._raw:
            return
        profile = self._raw["profile"]
        if (pixel_size):
            img_key = "image_%s" % pixel_size
            if img_key in profile:
                return profile[img_key]
        return profile[self._DEFAULT_IMAGE_KEY]