C# Need Help converting from Rigidbody to Character Controller

Hi everyone, I'm trying to convert the DontGoThroughThings script on the unify wiki so it will work with Character Controllers instead of rigidbodies. I'm getting this error from the console say charactercontroller doesn't exist in current context. How do you set it so that myCharacterController equals the Character Controller that is attached to the gameobject? Also if you see anything else wrong with my script please let me know.

 using UnityEngine;
 using System.Collections;
  
 public class DontGoThroughThings : MonoBehaviour 
 {
     public LayerMask layerMask; //make sure we aren't in this layer 
     public float skinWidth = 0.1f; //probably doesn't need to be changed 
  
     private float minimumExtent; 
     private float partialExtent; 
     private float sqrMinimumExtent; 
     private Vector3 previousPosition; 
     private CharacterController myCharacterController; 
  
  
     //initialize values 
     void Awake() 
     { 
        myCharacterController =  charactercontroller;
        previousPosition = myCharacterController.transform.position; 
        minimumExtent = Mathf.Min(Mathf.Min(collider.bounds.extents.x, collider.bounds.extents.y), collider.bounds.extents.z); 
        partialExtent = minimumExtent * (1.0f - skinWidth); 
        sqrMinimumExtent = minimumExtent * minimumExtent; 
     } 
  
     void FixedUpdate() 
     { 
        //have we moved more than our minimum extent? 
        Vector3 movementThisStep = myCharacterController.transform.position - previousPosition; 
        float movementSqrMagnitude = movementThisStep.sqrMagnitude;
  
        if (movementSqrMagnitude > sqrMinimumExtent) 
         { 
           float movementMagnitude = Mathf.Sqrt(movementSqrMagnitude);
           RaycastHit hitInfo; 
  
           //check for obstructions we might have missed 
           if (Physics.Raycast(previousPosition, movementThisStep, out hitInfo, movementMagnitude, layerMask.value)) 
              myCharacterController.transform.position = hitInfo.point - (movementThisStep/movementMagnitude)*partialExtent; 
        } 
  
        previousPosition = myCharacterController.transform.position; 
     }
 }