How to use the bless.ssh.public_keys.rsa_public_key.RSAPublicKey function in bless

def test_validation_for_signing():
    pub_key = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_1024)
    with pytest.raises(ValueError):
        pub_key.validate_for_signing()

    pub_key_sp = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_SMALLPRIME)
    with pytest.raises(ValueError):
        pub_key_sp.validate_for_signing()

    pub_key_e3 = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_E3)
    with pytest.raises(ValueError):
        pub_key_e3.validate_for_signing()

    pub_key_valid = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_2048)
    try:
        pub_key_valid.validate_for_signing()
    except ValueError:
        pytest.fail("Valid key failed to validate")

def test_validation_for_signing():
    pub_key = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_1024)
    with pytest.raises(ValueError):
        pub_key.validate_for_signing()

    pub_key_sp = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_SMALLPRIME)
    with pytest.raises(ValueError):
        pub_key_sp.validate_for_signing()

    pub_key_e3 = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_E3)
    with pytest.raises(ValueError):
        pub_key_e3.validate_for_signing()

    pub_key_valid = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_2048)
    try:
        pub_key_valid.validate_for_signing()
    except ValueError:
        pytest.fail("Valid key failed to validate")

def test_valid_key():
    pub_key = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY)
    assert 'Test RSA User Key' == pub_key.key_comment
    assert EXAMPLE_RSA_PUBLIC_KEY_N == pub_key.n
    assert EXAMPLE_RSA_PUBLIC_KEY_E == pub_key.e
    assert 'RSA 57:3d:48:4c:65:90:30:8e:39:ba:d8:fa:d0:20:2e:6c' == pub_key.fingerprint

def test_invalid_keys():
    with pytest.raises(TypeError):
        RSAPublicKey(EXAMPLE_ECDSA_PUBLIC_KEY)

    with pytest.raises(ValueError):
        RSAPublicKey('bogus')

def test_validation_for_signing():
    pub_key = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_1024)
    with pytest.raises(ValueError):
        pub_key.validate_for_signing()

    pub_key_sp = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_SMALLPRIME)
    with pytest.raises(ValueError):
        pub_key_sp.validate_for_signing()

    pub_key_e3 = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_E3)
    with pytest.raises(ValueError):
        pub_key_e3.validate_for_signing()

    pub_key_valid = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_2048)
    try:
        pub_key_valid.validate_for_signing()
    except ValueError:
        pytest.fail("Valid key failed to validate")

def test_invalid_keys():
    with pytest.raises(TypeError):
        RSAPublicKey(EXAMPLE_ECDSA_PUBLIC_KEY)

    with pytest.raises(ValueError):
        RSAPublicKey('bogus')

def get_basic_public_key(public_key):
    return RSAPublicKey(public_key)

def test_validation_for_signing():
    pub_key = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_1024)
    with pytest.raises(ValueError):
        pub_key.validate_for_signing()

    pub_key_sp = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_SMALLPRIME)
    with pytest.raises(ValueError):
        pub_key_sp.validate_for_signing()

    pub_key_e3 = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_E3)
    with pytest.raises(ValueError):
        pub_key_e3.validate_for_signing()

    pub_key_valid = RSAPublicKey(EXAMPLE_RSA_PUBLIC_KEY_2048)
    try:
        pub_key_valid.validate_for_signing()
    except ValueError:
        pytest.fail("Valid key failed to validate")

def __init__(self, ssh_public_key):
        """
        Extracts the useful RSA Public Key information from an SSH Public Key file.
        :param ssh_public_key: SSH Public Key file contents. (i.e. 'ssh-rsa AAAAB3NzaC1yc2E..').
        """
        super(RSAPublicKey, self).__init__()

        self.type = SSHPublicKeyType.RSA

        split_ssh_public_key = ssh_public_key.split(' ')
        split_key_len = len(split_ssh_public_key)

        # is there a key comment at the end?
        if split_key_len > 2:
            self.key_comment = ' '.join(split_ssh_public_key[2:])
        else:
            self.key_comment = ''

        public_key = serialization.load_ssh_public_key(ssh_public_key.encode('ascii'), default_backend())
        ca_pub_numbers = public_key.public_numbers()
        if not isinstance(ca_pub_numbers, RSAPublicNumbers):
            raise TypeError("Public Key is not the correct type or format")

def get_ssh_public_key(ssh_public_key):
    """
    Returns the proper SSHPublicKey instance based off of the SSH Public Key file.
    :param ssh_public_key: SSH Public Key file contents. (i.e. 'ssh-XXX AAAA....').
    :return: An SSHPublicKey instance.
    """
    if ssh_public_key.startswith(SSHPublicKeyType.RSA):
        rsa_public_key = RSAPublicKey(ssh_public_key)
        rsa_public_key.validate_for_signing()
        return rsa_public_key
    elif ssh_public_key.startswith(SSHPublicKeyType.ED25519):
        ed25519_public_key = ED25519PublicKey(ssh_public_key)
        return ed25519_public_key
    else:
        raise TypeError("Unsupported Public Key Type")