text: // Do not change any of the function names
  
  const returnFirst = (arr) => arr[0];
  const returnLast = (arr) => arr[arr.length - 1];
  const getArrayLength = (arr) => arr.length;
  const incrementByOne = (arr) => arr.map(x => ++x);
  const addItemToArray = (arr, item) => {
    arr.push(item);
    return arr;
  };
  const addItemToFront = (arr, item) => {
    arr.unshift(item);
    return arr;
  };
  const wordsToSentence = (words) => words.join(' ');
  const contains = (arr, item) => arr.includes(item);
  const addNumbers = (nums) => nums.reduce((a, b) => a + b);
  const averageTestScore = (testScores) => testScores.reduce((a, b) => a + b) / testScores.length;
  // const largestNumber = (nums) => nums.reduce((a, b) => a > b ? a : a = b);
  // const largestNumber = (nums) => nums.sort((a, b) => b - a)[0];
  const largestNumber = (nums) => Math.max(...nums);
  
  // Do not modify code below this line.
  // --------------------------------
  
  module.exports = {
    returnFirst: returnFirst,
    returnLast: returnLast,
    getArrayLength: getArrayLength,
    incrementByOne: incrementByOne,
    addItemToArray: addItemToArray,
    addItemToFront: addItemToFront,
    wordsToSentence: wordsToSentence,
    contains: contains,
    addNumbers: addNumbers,
    averageTestScore: averageTestScore,
    largestNumber: largestNumber,
  };
  