improve missing arg handling

- better error messages
- missing instrument is only allowed with 'list'
- missing argument to be replaced with ? in error message
- sea cli may now be given with 'graph' or 'sea' for service

__init__.py

@@ -49,7 +49,7 @@ class SewebManager(ServiceManager):
 
 
 all = NicosManager, FrappyManager, SeaManager, SewebManager
-
+KINDS = 'action', 'ins', 'service'
 
 def run(group, arglist):
     try:
@@ -68,7 +68,7 @@ def run(group, arglist):
            'service': lambda arg: arg in serv.services,
         }
 
-        for kind in 'action', 'ins', 'service':
+        for kind in KINDS:
             if arglist and arg_is[kind](arglist[0]):  # arg is of expected kind
                 args[kind] = arglist.pop(0)
                 continue
@@ -91,8 +91,11 @@ def run(group, arglist):
             args.setdefault('ins', serv.main_ins)
         if guessed_args:
             args.setdefault('action', 'gui')
-            print('do you mean:\n   %s %s %s %s %s' %
-                  (group, args.get('action', ''), args.get('ins', ''), args.get('service', ''), ' '.join(extra)))
+            guessed = [group] + [args.get(k, '') for k in KINDS] + extra
+            while not guessed[-1]:
+                guessed.pop()
+            guessed = ' '.join(a or '?' for a in guessed)
+            print(f'do you mean:\n   {guessed}')
         else:
             try:
                 serv.action(args['action'], *serv.treat_args(args, extra + arglist))