diff --git a/packages/stdlib/src/arrays/cluster/index.test.ts b/packages/stdlib/src/arrays/cluster/index.test.ts
index 1956c75..c0a8648 100644
--- a/packages/stdlib/src/arrays/cluster/index.test.ts
+++ b/packages/stdlib/src/arrays/cluster/index.test.ts
@@ -4,31 +4,37 @@ import { cluster } from '.';
 describe('cluster', () => {
   it('cluster an array into subarrays of a specific size', () => {
     const result = cluster([1, 2, 3, 4, 5, 6, 7, 8], 3);
+
     expect(result).toEqual([[1, 2, 3], [4, 5, 6], [7, 8]]);
   });
 
   it('handle arrays that are not perfectly divisible by the size', () => {
     const result = cluster([1, 2, 3, 4, 5], 2);
+
     expect(result).toEqual([[1, 2], [3, 4], [5]]);
   });
 
   it('return an array with each element in its own subarray if size is 1', () => {
     const result = cluster([1, 2, 3, 4], 1);
+
     expect(result).toEqual([[1], [2], [3], [4]]);
   });
 
   it('return an array with a single subarray if size is greater than the array length', () => {
     const result = cluster([1, 2, 3], 5);
+
     expect(result).toEqual([[1, 2, 3]]);
   });
 
   it('return an empty array if size is less than or equal to 0', () => {
     const result = cluster([1, 2, 3, 4], -1);
+
     expect(result).toEqual([]);
   });
 
   it('return an empty array if the input array is empty', () => {
     const result = cluster([], 3);
+    
     expect(result).toEqual([]);
   });
 });
\ No newline at end of file
diff --git a/packages/stdlib/src/arrays/sum/index.test.ts b/packages/stdlib/src/arrays/sum/index.test.ts
index a007487..6785353 100644
--- a/packages/stdlib/src/arrays/sum/index.test.ts
+++ b/packages/stdlib/src/arrays/sum/index.test.ts
@@ -4,36 +4,43 @@ import { sum } from '.';
 describe('sum', () => {
   it('return the sum of all elements in a number array', () => {
     const result = sum([1, 2, 3, 4, 5]);
+
     expect(result).toBe(15);
   });
 
   it('return 0 for an empty array', () => {
     const result = sum([]);
+
     expect(result).toBe(0);
   });
 
   it('return the sum of all elements using a getValue function', () => {
     const result = sum([{ value: 1 }, { value: 2 }, { value: 3 }], (item) => item.value);
+
     expect(result).toBe(6);
   });
 
   it('handle arrays with negative numbers', () => {
     const result = sum([-1, -2, -3, -4, -5]);
+
     expect(result).toBe(-15);
   });
 
   it('handle arrays with mixed positive and negative numbers', () => {
     const result = sum([1, -2, 3, -4, 5]);
+
     expect(result).toBe(3);
   });
 
   it('handle arrays with floating point numbers', () => {
     const result = sum([1.5, 2.5, 3.5]);
+
     expect(result).toBe(7.5);
   });
 
   it('handle arrays with a getValue function returning floating point numbers', () => {
     const result = sum([{ value: 1.5 }, { value: 2.5 }, { value: 3.5 }], (item) => item.value);
+    
     expect(result).toBe(7.5);
   });
 });
\ No newline at end of file
diff --git a/packages/stdlib/src/arrays/unique/index.test.ts b/packages/stdlib/src/arrays/unique/index.test.ts
index 4efcf04..bb4e30a 100644
--- a/packages/stdlib/src/arrays/unique/index.test.ts
+++ b/packages/stdlib/src/arrays/unique/index.test.ts
@@ -4,6 +4,7 @@ import { unique } from '.';
 describe('unique', () => {
   it('return an array with unique numbers', () => {
     const result = unique([1, 2, 3, 3, 4, 5, 5, 6]);
+
     expect(result).toEqual([1, 2, 3, 4, 5, 6]);
   });
 
@@ -12,16 +13,19 @@ describe('unique', () => {
       [{ id: 1 }, { id: 2 }, { id: 1 }],
       (item) => item.id,
     );
+
     expect(result).toEqual([{ id: 1 }, { id: 2 }]);
   });
 
   it('return the same array if all elements are unique', () => {
     const result = unique([1, 2, 3, 4, 5]);
+
     expect(result).toEqual([1, 2, 3, 4, 5]);
   });
 
   it('handle arrays with different types of values', () => {
     const result = unique([1, '1', 2, '2', 2, 3, '3']);
+
     expect(result).toEqual([1, '1', 2, '2', 3, '3']);
   });
 
@@ -29,11 +33,13 @@ describe('unique', () => {
     const sym1 = Symbol('a');
     const sym2 = Symbol('b');
     const result = unique([sym1, sym2, sym1]);
+    
     expect(result).toEqual([sym1, sym2]);
   });
 
   it('return an empty array when given an empty array', () => {
     const result = unique([]);
+
     expect(result).toEqual([]);
   });
 });
\ No newline at end of file
diff --git a/packages/stdlib/src/structs/stack/index.ts b/packages/stdlib/src/structs/stack/index.ts
index 6a6d1af..20c30f5 100644
--- a/packages/stdlib/src/structs/stack/index.ts
+++ b/packages/stdlib/src/structs/stack/index.ts
@@ -84,7 +84,7 @@ export class Stack<T> implements Iterable<T>, AsyncIterable<T> {
 
     /**
      * Pops an element from the stack
-     * @returns {T} The element popped from the stack
+     * @returns {T | undefined} The element popped from the stack
      */
     public pop() {
         return this.stack.pop();
@@ -92,7 +92,7 @@ export class Stack<T> implements Iterable<T>, AsyncIterable<T> {
 
     /**
      * Peeks at the top element of the stack
-     * @returns {T} The top element of the stack
+     * @returns {T | undefined} The top element of the stack
      */
     public peek() {
         if (this.isEmpty)