Enforce keyword order.

bparser.py

@@ -174,7 +174,7 @@ def p_args_multiple(t):
 def p_kwargs_multiple(t):
     'args : expression COLON statement COMMA args'
     args = t[5]
-    args.add_kwarg(t[1], t[3])
+    args.set_kwarg(t[1], t[3])
     t[0] = args
 
 def p_args_single_pos(t):

interpreter.py

@@ -616,6 +616,8 @@ class Interpreter():
 
     def reduce_arguments(self, args):
         assert(isinstance(args, nodes.Arguments))
+        if args.incorrect_order():
+            raise InvalidArguments('Line %d: all keyword arguments must be after positional arguments.' % args.lineno())
         reduced_pos = [self.reduce_single(arg) for arg in args.arguments]
         reduced_kw = {}
         for key in args.kwargs.keys():

nodes.py

@@ -186,6 +186,9 @@ class Arguments(Statement):
 
     def num_kwargs(self):
         return len(self.kwargs)
+    
+    def incorrect_order(self):
+        return self.order_error
 
     def __len__(self):
         return self.num_args() # Fixme