def _descExc(reprOfWhat, err):
    """Return a description of an exception.

    This is a private function for use by safeDescription().
    """
    try:
        return '(exception from repr(%s): %s: %s)' % (
            reprOfWhat, err.__class__.__name__, err)
    except Exception:
        return '(exception from repr(%s))' % reprOfWhat