The name `SmoothRandom' does not exist in the current context

heres my script. IDK why im getting thi error. it worked fine in someone elses vid.

using UnityEngine;
using System.Collections;

public class Bobber : MonoBehaviour {

    public float speed = 0.1f;
    public Vector3 range = new Vector3(1.5f, 1.5f, 1.5f);
    private Vector3 pos;
    // Use this for initialization
    void Start () 
        pos = transform.position;

    // Update is called once per frame
    void Update () {
    transform.position = pos + Vector3.Scale(SmoothRandom.GetVector3(speed), range);

If you don't have a SmoothRandom class then naturally that won't work. There's no SmoothRandom built into Unity.

You need to include Perlin.cs from Procedural example