text: const getFirstItem = (collection, cb) => {
    // invoke the callback function and pass the first item from the collection in as an argument
  };
  
  const getLength = (collection, cb) => {
    // Write a function called getLength that passes the length of the array into the callback
  };
  
  const getLastItem = (collection, cb) => {
    // Write a function called getLastItem which passes the getLastItem item of the array into the callback
  };
  
  const sumNums = (x, y, cb) => {
    // Write a function called sumNums that adds two numbers and passes the result to the callback
  };
  
  const multiplyNums = (x, y, cb) => {
    // Write a function called multiplyNums that multiplies two numbers and passes the result to the callback
  };
  
  const contains = (collection, item, cb) => {
    // Write a function called contains that checks if an item is present inside of the given array.
    // Pass true to the callback if it is, otherwise pass false
  };
  
  const removeDuplicates = (collection, cb) => {
    // Write a function called removeDuplicates that removes all duplicate values from the given array.
    // Pass the array to the callback function.  Do not mutate the original array.
  };
  
  module.exports = {
    getFirstItem,
    getLength,
    getLastItem,
    sumNums,
    multiplyNums,
    contains,
    removeDuplicates
  };
  