https://www.codewars.com/kata/counting-sheep-dot-dot-dot
Consider an array of sheep where some sheep may be missing from their place. We need a function that counts the number of sheep present in the array (true means present).
For example,
[true, true, true, false,
true, true, true, true ,
true, false, true, false,
true, false, false, true ,
true, true, true, true ,
false, false, true, true]
The correct answer would be 17.
Hint: Don't forget to check for bad values like null/undefined