+combine_posns FunOcc FunOcc = FunOcc -- see comment at FunOrArg defn
+combine_posns _ _ = ArgOcc
+
+{-
+multiplyBinderInfo orig@(ManyOcc _) new
+ = ManyOcc (min (getBinderInfoArity orig) (getBinderInfoArity new))
+
+multiplyBinderInfo orig new@(ManyOcc _)
+ = ManyOcc (min (getBinderInfoArity orig) (getBinderInfoArity new))
+
+multiplyBinderInfo (OneOcc posn1 dup1 scc1 n_alts1 ar_1)
+ (OneOcc posn2 dup2 scc2 n_alts2 ar_2)
+ = OneOcc (combine_posns posn1 posn2) ???
+-}
+