[comments are forwarded from Hartmut Kaiser, and translated from German]

1. stream::multiplexer is not part of the spec anymore, byt its referenced in 
   the object type enum.

2. Topic 'Session handling' (3.3.2) describes that a task can get queried for the
    object creating that task - the task has, however, no such API call.

3. What are the default contexts which should get associated with the default session?  
   Something like context(UserPass) with "anonymous@saga.org"? :-P

4. Topic 'Session Handling' references the exception IncorrectSession, 
   which is not defined in section 'Error Handling'.

5. What are the default contexts which are to be returned by session::list_contexts() ?
   Are these those which get added to the default session?

6. session::add_context is supposed to do nothing if the context to be added 
   already exists.  session::remove_context however is said to remove __all__ 
   identical matching contexts.  How is that to be understood?  As add_context 
   can never create duplicates, remove_context should always find only one 
   instance to remove, right?