function Update () {
var controller : CharacterController = GetComponent(CharacterController);
if (controller.isGrounded)
print("We are grounded");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
void Update() {
CharacterController controller = GetComponent<CharacterController>();
if (controller.isGrounded)
print("We are grounded");

}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

def Update():
controller as CharacterController = GetComponent[of CharacterController]()
if controller.isGrounded:
print('We are grounded')