Create MeanMode.js

Have the function MeanMode(arr) take the array of numbers stored in arr and return 1 if the mode equals the mean, 0 if they don't equal each other (ie. [5, 3, 3, 3, 1] should return 1 because the mode (3) equals the mean (3)). The array will not be empty, will only contain positive integers, and will not contain more than one mode.