How can i put a camera border in this script?

using System; using UnityEngine;

namespace UnityStandardAssets._2D { public class Camera2DFollow : MonoBehaviour { public Transform target; public float damping = 1; public float lookAheadFactor = 3; public float lookAheadReturnSpeed = 0.5f; public float lookAheadMoveThreshold = 0.1f;

     private float m_OffsetZ;
     private Vector3 m_LastTargetPosition;
     private Vector3 m_CurrentVelocity;
     private Vector3 m_LookAheadPos;

     // Use this for initialization
     private void Start()
     {
         m_LastTargetPosition = target.position;
         m_OffsetZ = (transform.position - target.position).z;
         transform.parent = null;
     }


     // Update is called once per frame
     private void Update()
     {
         // only update lookahead pos if accelerating or changed direction
         float xMoveDelta = (target.position - m_LastTargetPosition).x;

         bool updateLookAheadTarget = Mathf.Abs(xMoveDelta) > lookAheadMoveThreshold;

         if (updateLookAheadTarget)
         {
             m_LookAheadPos = lookAheadFactor*Vector3.right*Mathf.Sign(xMoveDelta);
         }
         else
         {
             m_LookAheadPos = Vector3.MoveTowards(m_LookAheadPos, Vector3.zero, Time.deltaTime*lookAheadReturnSpeed);
         }

         Vector3 aheadTargetPos = target.position + m_LookAheadPos + Vector3.forward*m_OffsetZ;
         Vector3 newPos = Vector3.SmoothDamp(transform.position, aheadTargetPos, ref m_CurrentVelocity, damping);

         transform.position = newPos;

         m_LastTargetPosition = target.position;
     }


 }

}