Copies from S3 to the local file system.  
            If the file already exists on the local file system than an ArgumentException is thrown.
            
 Parameters
 Parameters- destFileName (String)
- The path where to copy the file to.
 Return Value
 Return ValueFileInfo for the local file where file is copied to.
 Exceptions
 Exceptions| Exception | Condition | 
|---|---|
| IOException | If the file already exists locally. | 
| WebException | |
| AmazonS3Exception |