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 add_handles(self, model, forward_handle, backward_handle):
        """
        Add handles to all non-container layers in the model.
        Recursively for non-container layers
        """
        handles_list = []
        model_children = list(model.children())
        if model_children:
            for child in model_children:
                handles_list.extend(self.add_handles(child, forward_handle, backward_handle))
        else:  # leaves
            handles_list.append(model.register_forward_hook(forward_handle))
            handles_list.append(model.register_backward_hook(backward_handle))
        return handles_list