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 __init__(self, filename, errors):
        """
        :param filename: The name of the transaction file being replayed
        :param errors: a list of error classes or a string with an error description
        """

        # store args in case someone wants to read them from a caught exception
        self.filename = filename
        if isinstance(errors, (list, tuple)):
            self.errors = errors
        else:
            self.errors = [errors]

        if filename:
            msg = _('The following problems occurred while replaying the transaction from file "{filename}":').format(filename=filename)
        else:
            msg = _('The following problems occurred while running a transaction:')

        for error in self.errors:
            msg += "\n  " + str(error)

        super(TransactionReplayError, self).__init__(msg)