'Raises an exception if a symlink doesn\'t exist'

def _check_symlinks(self):

    for kind in ALL_FOUR:
        link = getattr(self, kind)
        if (not os.path.islink(link)):
            raise errors.CertStorageError('expected    {0}    to    be    a    symlink'.format(link))
        target = get_link_target(link)
        if (not os.path.exists(target)):
            raise errors.CertStorageError('target    {0}    of    symlink    {1}    does    not    exist'.format(target, link))
