SessionTransformer; checking for context existence

[Gerry Kaplan <gk...@kaplansoftware.com>]

Is there a way to check for the existence of a context in the session
transformer?
If you try and access the authentication context and it doesn't exist, it
will throw an error.
Is there a way to do a "getxml" and just let it return null or an empty
document if the context doesn't exist?