I get an error if i try to use flipX : 'SpriteRenderer' does not contain a definition for 'flipX'

here is the code I found on https://dev.to/bounasrnour/simple-unity-2d-platformer-ai-1hp8 :

 public class EnemyMovement : Enemys {

 //variables
 public int _moveSpeed;
 public int _attackDamage;
 public int _lifePoints;
 public float _attackRadius;

 public Transform playerTransfor;

 //movement
 public float _followRadius;
 //end
 [SerializeField] Transform playerTransform;
 [SerializeField] Animator enemyAnim;
 SpriteRenderer enemySR;

 void Start()
 {
     //get the player transform   
     playerTransform = FindObjectOfType<Player>().GetComponent<Transform>();
     //enemy animation and sprite renderer 
     enemyAnim = gameObject.GetComponent<Animator>();
     enemySR = GetComponent<SpriteRenderer>();
     //set the variables
     setMoveSpeed(_moveSpeed);
     setAttackDamage(_attackDamage);
     setLifePoints(_lifePoints);
     setAttackRadius(_attackRadius);
     setFollowRadius(_followRadius);
 }

 // Update is called once per frame
 void Update()
 {
     if (checkFollowRadius(playerTransform.position.x, transform.position.x))
     {
         //if player in front of the enemies
         if (playerTransform.position.x < transform.position.x)
         {

             if (checkAttackRadius(playerTransform.position.x, transform.position.x))
             {
                 //for attack animation
                 enemyAnim.SetBool("AttackA", true);
             }
             else
             {
                 this.transform.position += new Vector3(-getMoveSpeed() * Time.deltaTime, 0f, 0f);
                 //for attack animation
                 enemyAnim.SetBool("AttackA", false);
                 //walk
                 enemyAnim.SetBool("Walking", true);
                 enemySR.flipX = true;
             }

         }
         //if player is behind enemies
         else if (playerTransform.position.x > transform.position.x)
         {
             if (checkAttackRadius(playerTransform.position.x, transform.position.x))
             {
                 //for attack animation
                 enemyAnim.SetBool("AttackA", true);
             }
             else
             {
                 this.transform.position += new Vector3(getMoveSpeed() * Time.deltaTime, 0f, 0f);
                 //for attack animation
                 enemyAnim.SetBool("AttackA", false);
                 //walk
                 enemyAnim.SetBool("Walking", true);
                 enemySR.flipX = false;
             }


         }
     }
     else
     {
         enemyAnim.SetBool("Walking", false);
     }
 }

}