How to use the cryptography.utils.read_only_property function in cryptography

def __eq__(self, other):
        if not isinstance(other, CRLNumber):
            return NotImplemented

        return self.crl_number == other.crl_number

    def __ne__(self, other):
        return not self == other

    def __hash__(self):
        return hash(self.crl_number)

    def __repr__(self):
        return "".format(self.crl_number)

    crl_number = utils.read_only_property("_crl_number")


@utils.register_interface(ExtensionType)
class AuthorityKeyIdentifier(object):
    oid = ExtensionOID.AUTHORITY_KEY_IDENTIFIER

    def __init__(self, key_identifier, authority_cert_issuer,
                 authority_cert_serial_number):
        if (authority_cert_issuer is None) != (
            authority_cert_serial_number is None
        ):
            raise ValueError(
                "authority_cert_issuer and authority_cert_serial_number "
                "must both be present or both None"
            )

raise InvalidSignature
        return True


@utils.register_interface(ec.EllipticCurvePrivateKeyWithSerialization)
class _EllipticCurvePrivateKey(object):
    def __init__(self, backend, ec_key_cdata, evp_pkey):
        self._backend = backend
        _mark_asn1_named_ec_curve(backend, ec_key_cdata)
        self._ec_key = ec_key_cdata
        self._evp_pkey = evp_pkey

        sn = _ec_key_curve_sn(backend, ec_key_cdata)
        self._curve = _sn_to_elliptic_curve(backend, sn)

    curve = utils.read_only_property("_curve")

    def signer(self, signature_algorithm):
        if isinstance(signature_algorithm, ec.ECDSA):
            return _ECDSASignatureContext(
                self._backend, self, signature_algorithm.algorithm
            )
        else:
            raise UnsupportedAlgorithm(
                "Unsupported elliptic curve signature algorithm.",
                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM)

    def exchange(self, algorithm, peer_public_key):
        if not (
            self._backend.elliptic_curve_exchange_algorithm_supported(
                algorithm, self.curve
            )

def __eq__(self, other):
        if not isinstance(other, CRLNumber):
            return NotImplemented

        return self.crl_number == other.crl_number

    def __ne__(self, other):
        return not self == other

    def __hash__(self):
        return hash(self.crl_number)

    def __repr__(self):
        return "".format(self.crl_number)

    crl_number = utils.read_only_property("_crl_number")


@utils.register_interface(ExtensionType)
class AuthorityKeyIdentifier(object):
    oid = ExtensionOID.AUTHORITY_KEY_IDENTIFIER

    def __init__(self, key_identifier, authority_cert_issuer,
                 authority_cert_serial_number):
        if (authority_cert_issuer is None) != (
            authority_cert_serial_number is None
        ):
            raise ValueError(
                "authority_cert_issuer and authority_cert_serial_number "
                "must both be present or both None"
            )

other.authority_cert_serial_number
        )

    def __ne__(self, other):
        return not self == other

    def __hash__(self):
        if self.authority_cert_issuer is None:
            aci = None
        else:
            aci = tuple(self.authority_cert_issuer)
        return hash((
            self.key_identifier, aci, self.authority_cert_serial_number
        ))

    key_identifier = utils.read_only_property("_key_identifier")
    authority_cert_issuer = utils.read_only_property("_authority_cert_issuer")
    authority_cert_serial_number = utils.read_only_property(
        "_authority_cert_serial_number"
    )


@utils.register_interface(ExtensionType)
class SubjectKeyIdentifier(object):
    oid = ExtensionOID.SUBJECT_KEY_IDENTIFIER

    def __init__(self, digest):
        self._digest = digest

    @classmethod
    def from_public_key(cls, public_key):
        return cls(_key_identifier_from_public_key(public_key))

return encode_der(
        SEQUENCE,
        encode_der(INTEGER, encode_der_integer(r)),
        encode_der(INTEGER, encode_der_integer(s)),
    )


class Prehashed(object):
    def __init__(self, algorithm):
        if not isinstance(algorithm, hashes.HashAlgorithm):
            raise TypeError("Expected instance of HashAlgorithm.")

        self._algorithm = algorithm
        self._digest_size = algorithm.digest_size

    digest_size = utils.read_only_property("_digest_size")

return not self == other

    def __hash__(self):
        return hash((
            self.full_name,
            self.relative_name,
            self.only_contains_user_certs,
            self.only_contains_ca_certs,
            self.only_some_reasons,
            self.indirect_crl,
            self.only_contains_attribute_certs,
        ))

    full_name = utils.read_only_property("_full_name")
    relative_name = utils.read_only_property("_relative_name")
    only_contains_user_certs = utils.read_only_property(
        "_only_contains_user_certs"
    )
    only_contains_ca_certs = utils.read_only_property(
        "_only_contains_ca_certs"
    )
    only_some_reasons = utils.read_only_property("_only_some_reasons")
    indirect_crl = utils.read_only_property("_indirect_crl")
    only_contains_attribute_certs = utils.read_only_property(
        "_only_contains_attribute_certs"
    )


@utils.register_interface(ExtensionType)
class UnrecognizedExtension(object):
    def __init__(self, oid, value):
        if not isinstance(oid, ObjectIdentifier):

)

    def __eq__(self, other):
        if not isinstance(other, NoticeReference):
            return NotImplemented

        return (
            self.organization == other.organization and
            self.notice_numbers == other.notice_numbers
        )

    def __ne__(self, other):
        return not self == other

    organization = utils.read_only_property("_organization")
    notice_numbers = utils.read_only_property("_notice_numbers")


@utils.register_interface(ExtensionType)
class ExtendedKeyUsage(object):
    oid = ExtensionOID.EXTENDED_KEY_USAGE

    def __init__(self, usages):
        usages = list(usages)
        if not all(isinstance(x, ObjectIdentifier) for x in usages):
            raise TypeError(
                "Every item in the usages list must be an ObjectIdentifier"
            )

        self._usages = usages

    def __iter__(self):

return not self == other

    def __hash__(self):
        if self.full_name is not None:
            fn = tuple(self.full_name)
        else:
            fn = None

        if self.crl_issuer is not None:
            crl_issuer = tuple(self.crl_issuer)
        else:
            crl_issuer = None

        return hash((fn, self.relative_name, self.reasons, crl_issuer))

    full_name = utils.read_only_property("_full_name")
    relative_name = utils.read_only_property("_relative_name")
    reasons = utils.read_only_property("_reasons")
    crl_issuer = utils.read_only_property("_crl_issuer")


class ReasonFlags(Enum):
    unspecified = "unspecified"
    key_compromise = "keyCompromise"
    ca_compromise = "cACompromise"
    affiliation_changed = "affiliationChanged"
    superseded = "superseded"
    cessation_of_operation = "cessationOfOperation"
    certificate_hold = "certificateHold"
    privilege_withdrawn = "privilegeWithdrawn"
    aa_compromise = "aACompromise"
    remove_from_crl = "removeFromCRL"

"sect571k1": SECT571K1,

    "sect163r2": SECT163R2,
    "sect233r1": SECT233R1,
    "sect283r1": SECT283R1,
    "sect409r1": SECT409R1,
    "sect571r1": SECT571R1,
}


@utils.register_interface(EllipticCurveSignatureAlgorithm)
class ECDSA(object):
    def __init__(self, algorithm):
        self._algorithm = algorithm

    algorithm = utils.read_only_property("_algorithm")


def generate_private_key(curve, backend):
    return backend.generate_elliptic_curve_private_key(curve)


class EllipticCurvePublicNumbers(object):
    def __init__(self, x, y, curve):
        if (
            not isinstance(x, six.integer_types) or
            not isinstance(y, six.integer_types)
        ):
            raise TypeError("x and y must be integers.")

        if not isinstance(curve, EllipticCurve):
            raise TypeError("curve must provide the EllipticCurve interface.")

"Backend object does not implement HMACBackend.",
                _Reasons.BACKEND_MISSING_INTERFACE
            )

        if not isinstance(algorithm, hashes.HashAlgorithm):
            raise TypeError("Expected instance of hashes.HashAlgorithm.")
        self._algorithm = algorithm

        self._backend = backend
        self._key = key
        if ctx is None:
            self._ctx = self._backend.create_hmac_ctx(key, self.algorithm)
        else:
            self._ctx = ctx

    algorithm = utils.read_only_property("_algorithm")

    def update(self, data):
        if self._ctx is None:
            raise AlreadyFinalized("Context was already finalized.")
        if not isinstance(data, bytes):
            raise TypeError("data must be bytes.")
        self._ctx.update(data)

    def copy(self):
        if self._ctx is None:
            raise AlreadyFinalized("Context was already finalized.")
        return HMAC(
            self._key,
            self.algorithm,
            backend=self._backend,
            ctx=self._ctx.copy()