def problems(r, **attr):
 try:
  group_id = r.record.group_id
 except:
  raise HTTP(400)
 else:
  redirect(URL(f='group', args=[group_id, 'problem']))

def problems ( r , ** attr ) : try : group_id = r . record . group_id except : raise HTTP ( 400 ) else : redirect ( URL ( f = 'group' , args = [ group_id , 'problem' ] ) )
redirect to the list of problems for the group - used for a tab .