Update flatten.md

snippets/flatten.md

@@ -5,7 +5,7 @@ Flattens an array up to the specified depth.
 Use recursion, decrementing `depth` by 1 for each level of depth.
 Use `Array.reduce()` and `Array.concat()` to merge elements or arrays.
 Base case, for `depth` equal to `1` stops recursion.
-Omit the second element, `depth` to flatten only to a depth of `1` (single flatten).
+Omit the second argument, `depth` to flatten only to a depth of `1` (single flatten).
 
 ```js
 const flatten = (arr, depth = 1) =>