Onreadystatechange Expecting - Pass An Argument To A Function To Process Server Responses

I am trying to pass an argument to a function to process server responses. My original line of code looked like this: [url]

This works well enough as is, but I am trying to pass arguments to the function, and everything I am reading says to contruct the code like this: [url]

Every example I have come across uses this same approach, but I keep getting the error "Expected ';'" pointing to this line and then the code fails to execute. I just cannot see where there is anything missing, and it looks pretty much identical to my examples.

I have also tried replacing the call to the function with the actual code in long-form, and the result is the same.