Fix bugs

types/index.d.ts

@@ -0,0 +1,15 @@
+/**
+ * Sums up two numbers.
+ *
+ * @param {number} a The first number to add.
+ * @param {number} b The second number to add.
+ * @returns {number} The resulting sum of the two numbers.
+ */
+export declare function add(a: number, b: number): number
+/**
+ * Sums up a list of numbers.
+ *
+ * @param {number[]} numbers An array of numbers to add.
+ * @returns {number} The resulting sum of all the numbers.
+ */
+export declare function add(numbers: number[]): number