NOTE: DO NOT USE THE BUILT IN METHODS WHEN ASKED TO MAKE THEM!

1. Using Array.prototype add a new method myForEach that mimics the behaivor of the built in forEach.

2. Use your myForEach to add myMap to the Array prototype. myMap should behave the same as regular map.

3. Write a 'myFilterthat behave's the same asfilter`.

4. Write a myEvery.

5. Write a myReduce. It should use the first element in the array if none is given.

6. Write a myTranspose. This function should transpose a matrix. Exp:

let mtx = [
            [1, 2],
            [3, 4],
            [5, 6]
          ]

mtx.myTranspose();

// => [
        [1, 3, 5],
        [2, 4, 6]
       ]

7. Use myMap to build a new array where every element is incremented by 10.
8. Use myMap to build a new array where every non-string element is converted to an empty string.
9. Use myFilter to get only the even elements in an array.
10. Use myEvery to check if all elements in the array are the same.
11. Use myReduce to return the sum of every element in an array.
12. Use myMap to build a new array that doubles each element. Then chain myReduce to find the product of all the elements.
13. Use myReduce to find the largest number in an array.
14. Write a function elementDivisibleBy with parameters divisor and arr. Use myFilter to return a new array of every element of arr that can be evenly divided by divisor.
15. Write a myJoin function.
16. Write a mySlice function.
17. Write a function countZeroes, which takes an array of numbers as its argument and returns the amount of zeroes that occur in it. Use reduce.
18. Write a numberTimesIdx that uses map and multiples each number in the array by it's index.

Bonus: Write a myFlatten. This should take a multi-dimensional array and return it as one array.

let arr = [1, 2, [3, 4, 5, [6, 7, 8]]]
  arr.myFlatten();
  // => [1, 2, 3, 4, 5, 6, 7, 8]