Test migration to jest by hand

Apparently using regular expressions is way easier.

test/symmetricDifferenceWith/symmetricDifferenceWith.js

@@ -0,0 +1,5 @@
+const symmetricDifferenceWith = (arr, val, comp) => [
+...arr.filter(a => val.findIndex(b => comp(a, b)) === -1),
+...val.filter(a => arr.findIndex(b => comp(a, b)) === -1)
+];
+module.exports = symmetricDifferenceWith;