Rect.x  

var rect = Rect (10, 10, 100, 100);
print(rect.x);
rect.x = 20;

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Rect rect = new Rect(10, 10, 100, 100);
    void Example() {
        print(rect.x);
        rect.x = 20;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public rect as Rect = Rect(10, 10, 100, 100)

    def Example():
        print(rect.x)
        rect.x = 20