[det]http_open_session(-SessionID, 
+Options)Establish a new session. This is normally used if the create option is 
set to noauto. Options:
- renew(+Boolean)
 - If 
true (default false) and the current 
request is part of a session, generate a new session-id. By default, 
this predicate returns the current session as obtained with
http_in_session/1. 
- Errors
 permission_error(open, http_session, CGI) if this call is 
used after closing the CGI header. 
- See also
 - - http_set_session_options/1 
to control the 
create option. 
- http_close_session/1 
for closing the session.