Updated snippets

Mainly for better readability

snippets/sum-of-array-of-numbers.md

@@ -3,7 +3,6 @@
 Use `reduce()` to add each value to an accumulator, initialized with a value of `0`.
 
 ```js
-const sum = arr =>
-  arr.reduce( (acc , val) => acc + val, 0);
+const sum = arr => arr.reduce( (acc , val) => acc + val, 0);
 // sum([1,2,3,4]) -> 10
 ```