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 signal_handler_mapping(self):
        """A dict mapping (signal number) -> (a method handling the signal)."""
        # Could use an enum here, but we never end up doing any matching on the specific signal value,
        # instead just iterating over the registered signals to set handlers, so a dict is probably
        # better.
        return {
            signal.SIGINT: self._handle_sigint_if_enabled,
            signal.SIGQUIT: self.handle_sigquit,
            signal.SIGTERM: self.handle_sigterm,
        }