fix curly braces

snippets/isPrime.md

@@ -5,9 +5,10 @@ Checks if the provided integer is a prime number.
 Returns `false` if the provided number has positive divisors other than 1 and itself or if the number itself is less than 2.
 
 ```js
-const isPrime = num =>
+const isPrime = num => {
   for (var i = 2; i < num; i++) if (num % i == 0) return false;
   return num >= 2;
+}
 // isPrime(11) -> true
 // isPrime(12) -> false
 // isPrime(1) -> false