invoke repeating not working

i was trying invokeRepeating, but i couldn’t get how it works.below is the script i used for learning invokeRepeating. the script is for enemy, where he has to shoot projectiles for every 1 second. need help.

using UnityEngine;
using System.Collections;

public class cube_script : MonoBehaviour {
	public int speed = 5;
	public GameObject cubeProjectile;
	public float projectileOffset;
	Vector3 position;
	private float someValue = 0f;
	public Rigidbody projectile;
	// Update is called once per frame
	void Update () {
		//float amtToMove = speed * Time.fixedDeltaTime;
		//transform.Translate(Vector3.forward * amtToMove);
		//transform.rotation = Quaternion.Euler(new Vector3(0,0,100 * Time.time));
	void instantiating()
		Vector3 position = new Vector3(transform.position.x,transform.position.y, 
			                               transform.position.z + projectileOffset);		
		Instantiate(cubeProjectile, position, Quaternion.identity);
		Debug.Log(" instantiating ");
	void example()
		InvokeRepeating("instantiating", 0, 1F);

you need to call example() from start() or other place where you want.
but at least you have to call it once.