how to test for a layer in unity code example

Example 1: unity check collider layer

function OnCollisionEnter(collision : Collision)
 {
     if (collision.collider.gameObject.layer == LayerMask.NameToLayer("LAYER_NAME"))
     {
          Debug.Log("Touched a rail");
     }
 }

Example 2: Check object is in layermask unity

public bool IsInLayerMask(GameObject obj, LayerMask layerMask)
{
	return ((layerMask.value & (1 << obj.layer)) > 0);
}