text: /**
   * Determine if a 32-bit integer is a power of four
   * https://stackoverflow.com/a/19611541/8650340
   * @param {number} n
   * @return {boolean}
   */
  function isPowerOfFour(n) {
    return (n & -n & 0x55555554) === n;
  }
  
  console.log(isPowerOfFour(1)); // false
  console.log(isPowerOfFour(4)); // true
  console.log(isPowerOfFour(16)); // true
  console.log(isPowerOfFour(64)); // true
  console.log(isPowerOfFour(256)); // true
  