why unity executing only one yield

trying to run this code but it only print first debug

IEnumerator play() { yield return new WaitForSeconds(0.50f); Debug.LogError("1111111111111111"); yield return new WaitForSeconds(0.50f); Debug.LogError("2@@@@@222222222222"); yield return new WaitForSeconds(0.50f); Debug.LogError("3333333333333"); }