simple syntax issue with template

[Lloyd Dupont]

I'm trying to create 2 extra method for arrays ("range" would be better, 
though I don't quite understand what is a "range")
Although I have some indecipherable (to me) compiler error...

What's wrong with the code below?
==================
import std.algorithm;

public:

void remove(T)(ref T[] array, T element)
{
    auto index = array.countUntil!("a == b", T[], T)(array, element);
    removeAt(index);
}

void removeAt(T)(ref T[] array, sizediff_t index)
{
    if(index < 0 || index >= array.length)
        return;
    array.replaceInPlace(index, index + 1, []);
}


unittest
{
    auto a = [1, 3, 4];
    a.remove(3);
    assert(a == [1, 4]);
}
======================