proxy: imp docs

proxy/clock.go

@@ -2,13 +2,18 @@ package proxy
 
 import "time"
 
-// Clock is the interface for current time provider.  Its used to simplify
+// Clock is the interface for provider of current time.  It's used to simplify
 // testing.
+//
+// TODO(e.burkov):  Move to golibs.
 type Clock interface {
 	// Now returns the current local time.
 	Now() (now time.Time)
 }
 
+// type check
+var _ Clock = RealClock{}
+
 // RealClock is the [Clock] which actually uses the [time] package.
 type RealClock struct{}