def get_ed25519ll():
    """Lazy import-and-test of ed25519 module"""
    global ed25519ll

    if not ed25519ll:
        try:
            import ed25519ll  # fast (thousands / s)
        except (ImportError, OSError):  # pragma nocover
            from . import ed25519py as ed25519ll  # pure Python (hundreds / s)
        test()

    return ed25519ll