Market

- refactoring LatestBar(symbol string) (*Bar, error)

market.go

@@ -19,7 +19,7 @@ type Market interface {
 	IsMarketOpened() bool
 	Time() Clock
 
-	LatestBar(symbol string) (Bar, error)
+	LatestBar(symbol string) (*Bar, error)
 
 	Buy(ctx context.Context, symbol string, ratio float64) (Order, error)
 	Sell(ctx context.Context, symbol string, ratio float64) (Order, error)