# Part III — Functions, Recursion, Higher-Order Functions & Loops
fn double(x) {
  return x * 2;
}

fn apply_twice(f, val) {
  return f(f(val));
}

results = [];
for (i = 1; i <= 4; i = i + 1) {
  push(results, apply_twice(double, i));
}
println("Sequence: " + json_stringify(results));