text: // Understand the Problem
  // Input: String
  // Output: String
  
  // The function should:
  //  - Take a string as an argument
  //  - Return a new string with all letters doubled.
  
  // Implicit
  //  - If the argument is an empty string, an empty string should be returned.
  
  // Examples / Test Cases
  console.log(repeater('Hello')); // "HHeelllloo"
  console.log(repeater('Good job!')); // "GGoooodd  jjoobb!!"
  console.log(repeater('')); // ""
  
  // Data Structure
  // Array
  
  // Algorithm
  // Create a function that accepts a string as an argument.
  // Initialize an empty array to result.
  // Spread the string into an array.
  // For each element, append the current element to the result array twice.
  
  // Code
  function repeater(phrase) {
    const result = [];
    const phraseArray = [...phrase];
  
    phraseArray.forEach(item => result.push(item, item));
  
    return result.join('');
  }
  