Create a client for the Amazon SecurityTokenService Service with the credentials loaded from the application's
            default configuration, and if unsuccessful from the Instance Profile service on an EC2 instance.
            
            Example App.config with credentials set. 
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CopyC#<?xml version="1.0" encoding="utf-8" ?> <configuration> <appSettings> <add key="AWSAccessKey" value="********************"/> <add key="AWSSecretKey" value="****************************************"/> </appSettings> </configuration>
 Declaration Syntax
 Declaration Syntax| C# | 
public static AmazonSecurityTokenService CreateAmazonSecurityTokenServiceClient()
 Return Value
 Return ValueAn Amazon SecurityTokenService client
 Remarks
 Remarks