How can you read and understand the source of *naryFun in functional.d?

[Andrej Mitrovic]

Woops, sorry about the missing function definition after the line:
"unaryFun takes the string argument and might create this function:"

This should be maybe:
int unaryFun(int a)
{
    return (a & 1) == 0;
}

But that's oversimplification since that instantiation is a function
template itself, not a specific function.