Added subscription interfaces to universal client

commands.go

@@ -257,6 +257,11 @@ type StatefulCmdable interface {
 	ReadWrite() *StatusCmd
 }
 
+type Subscribable interface {
+	Subscribe(channels ...string) *PubSub
+	PSubscribe(channels ...string) *PubSub
+}
+
 var _ Cmdable = (*Client)(nil)
 var _ Cmdable = (*Tx)(nil)
 var _ Cmdable = (*Ring)(nil)

universal.go

@@ -113,6 +113,7 @@ func (o *UniversalOptions) simple() *Options {
 // applications locally.
 type UniversalClient interface {
 	Cmdable
+	Subscribable
 	Process(cmd Cmder) error
 	Close() error
 }