Set the mapper.
            
 Declaration Syntax
 Declaration Syntax| C# | 
[ObsoleteAttribute("The With methods are obsolete and will be removed in version 2 of the AWS SDK for .NET. See http://aws.amazon.com/sdkfornet/#version2 for more information.")] public StreamingStep WithMapper( string mapper )
 Parameters
 Parameters- mapper (String)
- The mapper.
 Return Value
 Return ValueA reference to this updated object so that method calls can be chained
            together.