Given an array of numbers, return an array which contains all the even numbers in the original array, which also have even indices.
get_only_evens([1, 3, 2, 6, 4, 8]) ➞ [2, 4]
get_only_evens([0, 1, 2, 3, 4]) ➞ [0, 2, 4]
get_only_evens([1, 2, 3, 4, 5]) ➞ []Arrays start at index 0.