export default (n) => {
  if (n <= 0) {
    throw new Error('Only positive numbers are allowed');
  }

  const iterate = (number, step) => {
    if (number === 1) {
      return step;
    }

    return number % 2 === 0 ? iterate(number / 2, step + 1) : iterate((3 * number) + 1, step + 1);
  };
  return iterate(n, 0);
};