* A function which accepts a number N and returns the Nth fibonacci number
{
    * We are passing a tuple of inputs into a graph here, such that the graph is
    * evaluated as an anonymous function. That anonymous function uses recur
    * internally to compute the result.
    out = {

        * A little helper function.
        decr = { out = add < (in, -1) };

        * Deconstruct the input tuple into its individual elements, for clarity.
        * There will be a more ergonomic way of doing this one day.
        n = tupEl < (in, 0);
        a = tupEl < (in, 1);
        b = tupEl < (in, 2);

        out = if < (
            isZero < n,
            a,
            recur < ( decr<n, b, add<(a,b) ),
        );

    } < (in, 0, 1);
}