fix test and description

client/backoff.go

@@ -8,7 +8,7 @@ import (
 
 type BackoffFunc func(ctx context.Context, req Request, attempts int) (time.Duration, error)
 
-// exponential backoff multiplied by a factor of 0.1 second.
+// exponential backoff is a function x^e multiplied by a factor of 0.1 second.
 func exponentialBackoff(ctx context.Context, req Request, attempts int) (time.Duration, error) {
 	return time.Duration(math.Pow(float64(attempts), math.E)) * time.Millisecond * 100, nil
 }