how to use rotate around in unity code example

Example 1: how to change rotate with script unity

var rotationVector = transform.rotation.eulerAngles;
rotationVector.z = 0;  //this number is the degree of rotation around Z Axis
transform.rotation = Quaternion.Euler(rotationVector);
//if you put this in a coroutine and yielding for some amount of time 
//you can have something like a rotating loading icon

Example 2: rotatearound unity

using UnityEngine;//Attach this script to a GameObject to rotate around the target position.
public class Example : MonoBehaviour
{
    private Vector3 target = new Vector3(5.0f, 0.0f, 0.0f);    void Update()
    {
        // Spin the object around the world origin at 20 degrees/second.
        transform.RotateAround(target, Vector3.up, 30 * Time.deltaTime);
    }
}