Simple code needed download S3 object to file like object

[Andrew Stuart]

I'm clearly looking in all the wrong places.

I just need to download a file from S3 and access it as a file like  
object which I can pass to some other object that is expecting a file  
like object with a read interface.

I just can't see how to do that. All I can see if a generator and the  
ability to download to a file on the disk which is not what I need.

Any help - a complete example - would be much appreciated.

thanks