generate new test that did already exist & update all module snippets with declaration

test/sortedIndex/sortedIndex.js

@@ -1,4 +1,4 @@
-module.exports = (arr, n) => {
+module.exports = sortedIndex = (arr, n) => {
 const isDescending = arr[0] > arr[arr.length - 1];
 const index = arr.findIndex(el => (isDescending ? n >= el : n <= el));
 return index === -1 ? arr.length : index;