Added a few type checking snippets from lodash

snippets/isSet.md

@@ -0,0 +1,13 @@
+### isSet
+
+Checks if value is classified as a Set object.
+
+Use the `instanceof`operator to check if the provided value is a `Set` object.
+
+```js
+const isSet = val => val instanceof Set;
+```
+
+```js
+isSet(new Set()); // true
+```