/// <summary>
 ///
 /// </summary>
 /// <param name="client">AWS DynamoDB client</param>
 /// <param name="settings">settings</param>
 public DynamoDBMutex(IAmazonDynamoDB client, DynamoDBMutexSettings settings = null)
 {
     _settings = settings ?? new DynamoDBMutexSettings();
     _client   = client;
 }
 /// <summary>
 /// Assumes access id and key are in the env vars or config
 /// </summary>
 /// <param name="endpoint">region</param>
 /// <param name="settings">settings</param>
 public DynamoDBMutex(RegionEndpoint endpoint, DynamoDBMutexSettings settings = null)
     : this(new AmazonDynamoDBClient(endpoint), settings)
 {
 }