1 files changed, 8 insertions, 0 deletions
diff --git a/src/extensions/ExtensionsTypings.ts b/src/extensions/ExtensionsTypings.ts
index d6ffd3be3..fa8851bb3 100644
--- a/src/extensions/ExtensionsTypings.ts
+++ b/src/extensions/ExtensionsTypings.ts
@@ -1,6 +1,14 @@
 /* eslint-disable @typescript-eslint/no-unused-vars */
 interface Array<T> {
+    /**
+     * returns the last element of the array or undefined
+     */
     lastElement(): T;
+    /**
+     * if val is in the list, it returns its index, otherwise undefined;
+     * @param val
+     */
+    getIndex(val: T): number | undefined;
 }
 
 interface String {