diff --git a/sum_of_digits_of_a_number.py b/sum_of_digits_of_a_number.py
index 64d62b281b7..f17fd6bcf41 100644
--- a/sum_of_digits_of_a_number.py
+++ b/sum_of_digits_of_a_number.py
@@ -13,6 +13,8 @@
     0
     >>> sum_of_digits(999)
     27
+    >>> sum_of_digits(-123)
+    6
 """
 
 import sys
@@ -49,8 +51,8 @@ def sum_of_digits(n: int) -> int:
     Compute the sum of the digits of an integer.
 
     Args:
-        n:Non-negative integer
-        If the integer is negative , it is converted to postive interger and assigned to same number
+        n: Non-negative integer.
+        If the integer is negative, it is converted to positive before computing the sum.
 
     Returns:
         Sum of digits of the number.
@@ -60,8 +62,10 @@ def sum_of_digits(n: int) -> int:
         6
         >>> sum_of_digits(405)
         9
+        >>> sum_of_digits(-789)
+        24
     """
-    n=abs(n)
+    n = abs(n)  # FIX: handle negative numbers
     total = 0
     while n > 0:
         # Add last digit and remove it from n
diff --git a/youtubedownloader.py b/youtubedownloader.py
index 80362a737f3..b4b813e7b5e 100644
--- a/youtubedownloader.py
+++ b/youtubedownloader.py
@@ -1,10 +1,15 @@
-from tkinter import Button, Entry, Label, Tk, filedialog, messagebox
-from threading import Thread
-from pytube import YouTube
+# modules for Using of app
+from tkinter import Button, Entry, Label, Tk, filedialog, messagebox # Gui Modules 
+from threading import Thread # modules for multi threding 
+from pytube import YouTube # Module for Youtube service
+
+# this function for mulple code runes at a time 
 def threading():
     # Call work function
     t1 = Thread(target=download)
     t1.start()
+
+# this function for Download Youtube video
 def download():
     try:
         url = YouTube(str(url_box.get()))
@@ -18,7 +23,7 @@ def download():
         else:
             messagebox.showwarning("", "Download cancelled!")
     except Exception:
-        messagebox.showerror("Error", "An error occurred while downloading the video.")
+        messagebox.showerror("Error", "Some Thing Went Wrong!!!\nplease try again")
 
         
 # This code runes on only this file
@@ -40,13 +45,15 @@ def download():
     )
     introlable.place(x=35, y=20)
 
-    Label(root, text="Enter YouTube Link", font=("sans-serif", 16), bg="olivedrab1").place(
+    Label(root, text="Enter YouTube Link", font=("sans-serif", 16), bg="olivedrab1", fg='Black').place(
         x=40, y=150
     )
 
+    # entry box in UI
     url_box = Entry(root, font=("arial", 30), width=30)
     url_box.place(x=40, y=180)
 
+    # download button in UI
     btn = Button(root, text="DOWNLOAD", font=("sans-serif", 25), command=threading)
     btn.place(x=270, y=240)
     root.mainloop()