echo: "\n" option implemented.

echo/echo.go

@@ -7,15 +7,18 @@ import (
 )
 
 func Run(args []string) int {
+	var nflag bool
 	flagSet := flag.NewFlagSet(args[0], flag.ExitOnError)
+	flagSet.BoolVar(&nflag, "n", false, "Do not print new line character.")
 	flagSet.Parse(args[1:])
-	args = args[1:]
-	status := 0
+	args = flagSet.Args()
 	l := len(args) - 1
 	for i, s := range args {
 		fmt.Print(s)
 		if i!=l { fmt.Print(" ") }
 	}
+	if !nflag {
 		fmt.Print("\n")
-	return status
+	}
+	return 0
 }