Getting several BCE0044 compiler errors for OnCollisionEnter. Is my syntax wrong?

Below is the problematic UnityScript that I have attempted to isolate:

var isCollideTurning : boolean;
function FixedUpdate () {

    function OnCollisionEnter (){
        isCollideTurning = true;
    }
}

Even when I compiled it in an empty project, specially created for testing, I still get the following errors:

Script.js(7,34): BCE0044: expecting :, found '='.

Script.js(6,18): BCE0044: expecting (, found 'OnCollisionEnter'.

Script.js(6,37): UCE0001: ';' expected. Insert a semicolon at the end.

I have only been coding in UnityScript for under a week, and have no prior coding experience so I am not sure if I have simply made a glaring syntax error.

Could someone tell me what I am doing wrong?

You cant have a function inside another function(as far as i am aware!).

You are declaring a function within a function. That is not possible. Move the inner function OnCollisionEnter outside of the brackets of the FixedUpdate function.

Don't ever put a function into a function! That means, no OnCollisionEnter in FixedUpdate. Just write:

var isCollideTurning : boolean;

function FixedUpdate () 
{

}

function OnCollisionEnter (){
    isCollideTurning = true;
}

In this example, FixedUpdate doesn't contain anything so you can remove it simply if you want. So, everything you need is this:

var isCollideTurning : boolean;

function OnCollisionEnter (){
    isCollideTurning = true;
}

You can't declare a function in a function you maniac.