def METHOD_NAME(delete=True):
    """Create temporary file for fake authorisation hmac signing key.
    :returns: Instance of :class:`~.NamedTemporaryFile`, whose *data*
      attribute contains the HMAC signing binary key."""
    t = NamedTemporaryFile(delete=delete)
    with open("/dev/urandom", "rb") as fd:
        t.data = fd.read(20)
    t.write(t.data)
    t.seek(0)
    return t