var a = new A #alt1# var a = new B
a.foo(a=1,b=2,3,4,e=5,f=6)
a.foo(f=6,3,e=5,b=2,4,a=1)
-a.foo(3,e=5,b=2,4)
+#alt3#a.foo(3,e=5,b=2,4)
var b = new B #alt1# var b = new A
b.foo(x=1,y=2,3,4,u=5,v=6)
b.foo(v=6,3,u=5,y=2,4,x=1)
-b.foo(3,u=5,y=2,4)
+#alt3#b.foo(3,u=5,y=2,4)