unity letters apears slowly code example

Example: unity letters apears slowly

using UnityEngine;
using System.Collections;
 
public class AutoType : MonoBehaviour {
 
	public float letterPause = 0.2f;
	public AudioClip sound;
 
	string message;
 
	// Use this for initialization
	void Start () {
		message = guiText.text;
		guiText.text = "";
		StartCoroutine(TypeText ());
	}
 
	IEnumerator TypeText () {
		foreach (char letter in message.ToCharArray()) {
			guiText.text += letter;
			if (sound)
				audio.PlayOneShot (sound);
				yield return 0;
			yield return new WaitForSeconds (letterPause);
		}      
	}
}