error CS1525: Unexpected symbol `)', expecting `('

I am trying to ignore colliders in my scene . I did the by number layers and I gotten an error . The player has a collider and so do the enemy ai’s . The enemy ai’s on the default layer . I am trying to avoid the default layers . When the player collide in the enemy ai the player leg flop up and down and the enemy is the stuck on the player . Anywhere the player moves the enemy ai stays on the player.

Here is my script :

using UnityEngine;
using System.Collections;

public class laying : MonoBehaviour {

	// Use this for initialization
	void start () {
	Physics.IgnoreLayerCollision(default);
	}
	
	// Update is called once per frame
	void Update () {
	
	}
}

Physics.IgnoreLayerCollision(default);
is wrong. Try:

Physics.IgnoreLayerCollision(LayerMask.NameToLayer("Default"));