Clean up the oopsie. Rebuild the blank exercises.

node_modules/lodash/_isIndex.js

@@ -13,10 +13,13 @@ var reIsUint = /^(?:0|[1-9]\d*)$/;
  * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
  */
 function isIndex(value, length) {
+  var type = typeof value;
   length = length == null ? MAX_SAFE_INTEGER : length;
+
   return !!length &&
-    (typeof value == 'number' || reIsUint.test(value)) &&
-    (value > -1 && value % 1 == 0 && value < length);
+    (type == 'number' ||
+      (type != 'symbol' && reIsUint.test(value))) &&
+        (value > -1 && value % 1 == 0 && value < length);
 }
 
 module.exports = isIndex;