function fibonacci(n) {
  if (n == 0) {
    return 0;
  } else if (n == 1) {
    return 1;
  } else {
    return fibonacci(n - 2) + fibonacci(n - 1);
  }
}
Computes the desired fibonacci number.
@param {number} n The nth desired fibonacci number.
@return {number} The nth fibonacci number.