Errata

I think the following paragraphs of descripting the typeerror is wrong, as I've debugged it in my local env:

TypeError: "listener" argument must be a function
This means that in the last line, getBody.getResult is not a function.

I think the error is not caused by "getBody.getResult is not a function", the reason is the "this" in the "result.on('data', this.saveBody);" statement is ClientRequest object instead of the getBody object, so "this.saveBody" will be undifined, that's why the error presented.

Two mistakes:
- inner "return" omitted, so output = undefined
- naming the inner parameter "numberOne" overrides the partially applied outer parameter
so actual output:
add(1)(2) = 2 + undefined = NaN
rather than desired:
add(1)(2) = 2 + 1 = 3

The code:

/* original version */
function add(numberOne, numberTwo){
return function(numberOne){
numberOne + numberTwo;
};
};

/* corrected version */
function add(numberOne, numberTwo){
return function(numberTwo){
return numberOne + numberTwo;
};
};