something about the C# script in Unity live session

hi everyone , i just downloaded the sample assets from the asset store ,and there is a 2D character in it and the tutorials video "2D chracter controller" has used before,here the script whthin the 2D character prefab:

Code (CSharp):

1. using UnityEngine;
2.  
3. [RequireComponent(typeof(PlatformerCharacter2D))]
4. public class Platformer2DUserControl : MonoBehaviour
5. {
6.     private PlatformerCharacter2D character;
7.     private bool jump;
8.  
9.  
10.     void Awake()
11.     {
12.         character = GetComponent<PlatformerCharacter2D>();
13.     }
14.  
15.     void Update ()
16.     {
17.         // Read the jump input in Update so button presses aren't missed.
18. #if CROSS_PLATFORM_INPUT
19.         if (CrossPlatformInput.GetButtonDown("Jump")) jump = true;
20. #else
21.         if (Input.GetButtonDown("Jump")) jump = true;
22. #endif
23.  
24.     }
25.  
26.     void FixedUpdate()
27.     {
28.         // Read the inputs.
29.         bool crouch = Input.GetKey(KeyCode.LeftControl);
30.         #if CROSS_PLATFORM_INPUT
31.         float h = CrossPlatformInput.GetAxis("Horizontal");
32.         #else
33.         float h = Input.GetAxis("Horizontal");
34.         #endif
35.  
36.         // Pass all parameters to the character control script.
37.         character.Move( h, crouch , jump );
38.  
39.         // Reset the jump input once it has been used.
40.         jump = false;
41.     }
42. }
43.  

and my question is : where is the CrossPlatformInput? i cant find it in the assets package and Unity Scripting API neither