append - too many files

[Joel via Digitalmars-d-learn]

I get this error after a while (seems append doesn't close the 
file each time):
std.file.FileException@std/file.d(836): history.txt: Too many 
open files

```d
auto jm_addToHistory(T...)(T args) {
        import std.conv : text;
        import std.file : append;
        auto txt = text(args);
        append("history.txt", txt);

        return txt;
}
```