diff --git a/Course3/Lab4/validations.py b/Course3/Lab4/validations.py
index b18de65a2e..7bc0335893 100644
--- a/Course3/Lab4/validations.py
+++ b/Course3/Lab4/validations.py
@@ -1,24 +1,55 @@
-#!/usr/bin/env python3
 
 import re
 
+
+
 def validate_user(username, minlen):
+
     """Checks if the received username matches the required conditions."""
+
     if type(username) != str:
+
         raise TypeError("username must be a string")
+
     if minlen < 1:
+
         raise ValueError("minlen must be at least 1")
+
     
+
     # Usernames can't be shorter than minlen
+
     if len(username) < minlen:
+
         return False
+
     # Usernames can only use letters, numbers, dots and underscores
+
     if not re.match('^[a-z0-9._]*$', username):
+
         return False
+
     # Usernames can't begin with a number
+
     if username[0].isnumeric():
+
         return False
+
+    # Usernames can't begin with '.' or '_'
+
+    if username[0] in "._":
+
+        return False
+
     return True
 
 
 
+print(validate_user("blue.kale", 3))       # True
+
+print(validate_user(".blue.kale", 3))      # False
+
+print(validate_user("red_quinoa", 4))      # True
+
+print(validate_user("_red_quinoa", 4))     # False
+