Unity and Light with C# ... [HELP]

function Update () {
	
	if(Input.GetKeyDown(KeyCode.F)){
		if(light.enabled == true)
			light.enabled = false;
		else
			light.enabled = true;
			}
			}

void Update () {
		if(Input.GetKey(KeyCode.F)){
			if(light.enabled = true){
				light.enabled = false;
			}
			else{
				Light.enabled = true;
			}
		}
	}

    void Update()
    {
        if (Input.GetKey(KeyCode.F))
        {
            light.enabled = !light.enabled;
        }
    }

using UnityEngine;
using System.Collections;

public class flashing : MonoBehaviour {
	// Update is called once per frame
	void Update () {
		if(Input.GetKey(KeyCode.F)){
			if(light.enabled == true){
				light.enabled = false;
			}
			else{
				Light.enabled = true;
			}
		}
	}
	
}

Input.GetKey

 Input.GetKeyDown