How to use the msrest.authentication.Authentication function in msrest

def setUp(self):

        cfg = Configuration("https://my_service.com")
        cfg.retry_policy.backoff_factor=0
        cfg.redirect_policy.max_redirects=2
        cfg.credentials = Authentication()

        self.client = ServiceClient(None, cfg)

        return super(TestRedirect, self).setUp()

# Allow overriding resource manager URI using environment variable
    # for testing purposes. Subscription id is also determined by environment
    # variable.
    rm_uri_override = getenv(RM_URI_OVERRIDE)
    if rm_uri_override:
        client_id = getenv(CLIENT_ID)
        if client_id:
            from azure.common.credentials import ServicePrincipalCredentials
            credentials = ServicePrincipalCredentials(
                client_id=client_id,
                secret=getenv(CLIENT_SECRET),
                tenant=getenv(TENANT_ID))
        else:
            from msrest.authentication import Authentication    # pylint: disable=import-error
            credentials = Authentication()

        return MariaDBManagementClient(
            subscription_id=getenv(SUB_ID_OVERRIDE),
            base_url=rm_uri_override,
            credentials=credentials)
    # Normal production scenario.
    return get_mgmt_service_client(cli_ctx, MariaDBManagementClient)

# Allow overriding resource manager URI using environment variable
    # for testing purposes. Subscription id is also determined by environment
    # variable.
    rm_uri_override = getenv(RM_URI_OVERRIDE)
    if rm_uri_override:
        client_id = getenv(CLIENT_ID)
        if client_id:
            from azure.common.credentials import ServicePrincipalCredentials
            credentials = ServicePrincipalCredentials(
                client_id=client_id,
                secret=getenv(CLIENT_SECRET),
                tenant=getenv(TENANT_ID))
        else:
            from msrest.authentication import Authentication    # pylint: disable=import-error
            credentials = Authentication()

        return MySQLManagementClient(
            subscription_id=getenv(SUB_ID_OVERRIDE),
            base_url=rm_uri_override,
            credentials=credentials)
    # Normal production scenario.
    return get_mgmt_service_client(cli_ctx, MySQLManagementClient)

# Allow overriding resource manager URI using environment variable
    # for testing purposes. Subscription id is also determined by environment
    # variable.
    rm_uri_override = getenv(RM_URI_OVERRIDE)
    if rm_uri_override:
        client_id = getenv(CLIENT_ID)
        if client_id:
            from azure.common.credentials import ServicePrincipalCredentials
            credentials = ServicePrincipalCredentials(
                client_id=client_id,
                secret=getenv(CLIENT_SECRET),
                tenant=getenv(TENANT_ID))
        else:
            from msrest.authentication import Authentication    # pylint: disable=import-error
            credentials = Authentication()

        return MySQLManagementClient(
            subscription_id=getenv(SUB_ID_OVERRIDE),
            base_url=rm_uri_override,
            credentials=credentials)
    # Normal production scenario.
    return get_mgmt_service_client(cli_ctx, MySQLManagementClient)

# Allow overriding resource manager URI using environment variable
    # for testing purposes. Subscription id is also determined by environment
    # variable.
    rm_uri_override = getenv(RM_URI_OVERRIDE)
    if rm_uri_override:
        client_id = getenv(CLIENT_ID)
        if client_id:
            from azure.common.credentials import ServicePrincipalCredentials
            credentials = ServicePrincipalCredentials(
                client_id=client_id,
                secret=getenv(CLIENT_SECRET),
                tenant=getenv(TENANT_ID))
        else:
            from msrest.authentication import Authentication    # pylint: disable=import-error
            credentials = Authentication()

        return PostgreSQLManagementClient(
            subscription_id=getenv(SUB_ID_OVERRIDE),
            base_url=rm_uri_override,
            credentials=credentials)
    # Normal production scenario.
    return get_mgmt_service_client(cli_ctx, PostgreSQLManagementClient)

sign_key = '%s\n%d' % (encoded_uri, ttl)
        signature = b64encode(HMAC(b64decode(self.key), sign_key.encode('utf-8'), sha256).digest())

        result = {
            'sr': self.uri,
            'sig': signature,
            'se': str(ttl)
        }

        if self.policy:
            result['skn'] = self.policy

        return 'SharedAccessSignature ' + urlencode(result)


class BasicSasTokenAuthentication(Authentication):
    """
    Basic Shared Access Signature authorization for Azure IoT Hub.

    Args:
        sas_token (str): sas token to use in authentication.
    """
    def __init__(self, sas_token):
        self.sas_token = sas_token

    def signed_session(self):
        """
        Create requests session with SAS auth headers.

        Returns:
            session (): requests.Session.
        """

def signed_session(self, session=None):
        # type: (Optional[requests.Session]) -> requests.Session
        """Create requests session with any required auth headers applied.

        If a session object is provided, configure it directly. Otherwise,
        create a new session and return it.

        :param session: The session to configure for authentication
        :type session: requests.Session
        :rtype: requests.Session
        """
        return session or requests.Session()


class BasicAuthentication(Authentication):
    """Implementation of Basic Authentication.

    :param str username: Authentication username.
    :param str password: Authentication password.
    """

    def __init__(self, username, password):
        # type: (str, str) -> None
        self.scheme = 'Basic'
        self.username = username
        self.password = password

    def signed_session(self, session=None):
        # type: (Optional[requests.Session]) -> requests.Session
        """Create requests session with any required auth headers
        applied.