Hide golang messages

Is it possible to hide the golang messages? I show you an example:

package main

import (
	"flag"
	"fmt"
	"os"
)

var signal = flag.String("z", "", "")

func main() {

	flag.Usage = func() {
		fmt.Printf("Usage: kata -z <command>\n\n")
		fmt.Printf("    test\tTesting\n")
		fmt.Printf("    version\tVersion\n")
		fmt.Println("")
	}

	flag.Parse()
	if len(os.Args) != 3 {
		flag.Usage()
		os.Exit(1)
	}

	switch *signal {
	case "test":
		fmt.Println("testing...")
	case "version":
		fmt.Println("0.0.1")
	default:
		fmt.Println("incorrect...")
	}
}

This app show to user the next information:
https://play.golang.org/p/oYwADdmlAJ

But if I write in the command-line kata -flag, the system returns: flag needs an argument: or flag provided but not defined: and the information that I show you before.

I would like to know if it's possible to hide the golang messages?

P.S.: If you don't understand my question, I can rephrase.

Using the global functions in flag actually passes through to a global flag.FlagSet called flag.CommandLine. Internally, this prints errors to an output, which is stderr by default. You can suppress the messages by setting this explicitly to, for example, ioutil.Discard:

flag.CommandLine.SetOutput(ioutil.Discard)
flag.Parse()

This will discard all messages output internally by flag.Parse(). You could also log it to anywhere else you choose by passing in an appropriate io.Writer.

I have found a solution:

Before:

flag.Parse()
if len(os.Args) != 3 {
    flag.Usage()
    os.Exit(1)
}

Now:

if len(os.Args) != 3 || os.Args[1] != "-z" {
	flag.Usage()
	os.Exit(1)
} else {
	flag.Parse()
}