Use idiomatic js

Intentionally used the word `rest` instead of `args` because I felt for this case rest better helps people understand that , rest holds all the args after first arg. If I have used `args` then it partly implies that first is not an arg which is not true

snippets/flip.md

@@ -4,16 +4,16 @@ Flip takes a function as an argument, then makes the first argument the last.
 
 Return a closure that takes variadic inputs, and splices the last argument to make it the first argument before applying the rest.
 
-```js
-const flip = fn => (...args) => fn(args.pop(), ...args);
+```js
+const flip = fn => (first, ...rest) => fn(...rest, first);
 ```
 
-```js
-let a = { name: 'John Smith' };
-let b = {};
-const mergeFrom = flip(Object.assign);
-let mergePerson = mergeFrom.bind(null, a);
-mergePerson(b); // == b
-b = {};
-Object.assign(b, a); // == b
+```js
+let a = { name: 'John Smith' };
+let b = {};
+const mergeFrom = flip(Object.assign);
+let mergePerson = mergeFrom.bind(null, a);
+mergePerson(b); // == b
+b = {};
+Object.assign(b, a); // == b
 ```