diff --git a/demo/src/__init___.py b/demo/src/__init___.py
new file mode 100644
index 0000000..e69de29
diff --git a/demo/src/password_checker.py b/demo/src/password_checker.py
new file mode 100644
index 0000000..5a7885a
--- /dev/null
+++ b/demo/src/password_checker.py
@@ -0,0 +1,58 @@
+class PasswordChecker:
+    def __init__(self):
+        self.min_length = 8
+        self.special_chars = "!@#$%^&*()_+-=[]{}|;:,.<>?"
+    
+    def check_strength(self, password):
+        """
+        Bug: The function doesn't properly check for the presence of numbers
+        It only checks if there's a digit in the first position
+        """
+        score = 0
+        feedback = []
+        
+        # Check length
+        if len(password) >= self.min_length:
+            score += 1
+        else:
+            feedback.append("Password should be at least 8 characters long")
+        
+        # Check for uppercase
+        if any(c.isupper() for c in password):
+            score += 1
+        else:
+            feedback.append("Password should contain at least one uppercase letter")
+        
+        # Bug: Incorrect number checking
+        if password[0].isdigit():  # Bug is here - only checks first character
+            score += 1
+        else:
+            feedback.append("Password should contain at least one number")
+        
+        # Check for special characters
+        if any(c in self.special_chars for c in password):
+            score += 1
+        else:
+            feedback.append("Password should contain at least one special character")
+        
+        strength = {
+            0: "Very Weak",
+            1: "Weak",
+            2: "Moderate",
+            3: "Strong",
+            4: "Very Strong"
+        }
+        
+        return {
+            "score": score,
+            "strength": strength[score],
+            "feedback": feedback
+        }
+
+# Usage Example
+if __name__ == "__main__":
+    checker = PasswordChecker()
+    test_password = "2weakpass"
+    result = checker.check_strength(test_password)
+    print(f"Password Strength: {result['strength']}")
+    print("Feedback:", "\n".join(result['feedback']))
\ No newline at end of file
diff --git a/demo/src/student_management.py b/demo/src/student_management.py
new file mode 100644
index 0000000..b0a8b14
--- /dev/null
+++ b/demo/src/student_management.py
@@ -0,0 +1,49 @@
+class Student:
+    def __init__(self, roll_no, name, age, grade):
+        self.roll_no = roll_no
+        self.name = name
+        self.age = age
+        self.grade = grade
+
+class StudentManagementSystem:
+    def __init__(self):
+        self.students = []
+    
+    def add_student(self, roll_no, name, age, grade):
+        """
+        Bug: Function doesn't properly check for duplicate roll numbers
+        It compares strings instead of integers for roll numbers
+        """
+        # Bug: Incorrect string comparison instead of integer comparison
+        if any(str(student.roll_no) == str(roll_no) for student in self.students):
+            return False, "Roll number already exists"
+        
+        new_student = Student(roll_no, name, age, grade)
+        self.students.append(new_student)
+        return True, "Student added successfully"
+    
+    def get_student(self, roll_no):
+        for student in self.students:
+            if student.roll_no == roll_no:
+                return student
+        return None
+    
+    def display_all_students(self):
+        if not self.students:
+            return "No students registered"
+        
+        result = "Student List:\n"
+        for student in self.students:
+            result += f"Roll No: {student.roll_no}, Name: {student.name}, "
+            result += f"Age: {student.age}, Grade: {student.grade}\n"
+        return result
+
+# Usage Example
+if __name__ == "__main__":
+    sms = StudentManagementSystem()
+    
+    # These additions will work even though they should be duplicates
+    sms.add_student("001", "John Doe", 18, "A")
+    sms.add_student(1, "Jane Smith", 19, "B")    # Should be rejected but won't be
+    
+    print(sms.display_all_students())
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diff --git a/demo/src/todo_list.py b/demo/src/todo_list.py
new file mode 100644
index 0000000..b19275c
--- /dev/null
+++ b/demo/src/todo_list.py
@@ -0,0 +1,63 @@
+class Task:
+    def __init__(self, id, title, description):
+        self.id = id
+        self.title = title
+        self.description = description
+        self.status = "pending"  # Can be "pending", "in_progress", or "completed"
+        self.is_completed = False  # Bug: Redundant status tracking
+
+class TodoList:
+    def __init__(self):
+        self.tasks = []
+        self.next_id = 1
+    
+    def add_task(self, title, description):
+        task = Task(self.next_id, title, description)
+        self.tasks.append(task)
+        self.next_id += 1
+        return task.id
+    
+    def update_status(self, task_id, new_status):
+        """
+        Bug: Status inconsistency between status field and is_completed flag
+        """
+        task = self.get_task(task_id)
+        if not task:
+            return False, "Task not found"
+        
+        if new_status not in ["pending", "in_progress", "completed"]:
+            return False, "Invalid status"
+        
+        task.status = new_status
+        # Bug: is_completed flag is not updated
+        # This creates inconsistency in task completion status
+        return True, "Status updated successfully"
+    
+    def get_task(self, task_id):
+        for task in self.tasks:
+            if task.id == task_id:
+                return task
+        return None
+    
+    def list_tasks(self):
+        if not self.tasks:
+            return "No tasks found"
+        
+        result = "Task List:\n"
+        for task in self.tasks:
+            result += f"ID: {task.id}, Title: {task.title}\n"
+            result += f"Description: {task.description}\n"
+            result += f"Status: {task.status}, Completed: {task.is_completed}\n"
+            result += "-" * 50 + "\n"
+        return result
+
+# Usage Example
+if __name__ == "__main__":
+    todo = TodoList()
+    
+    # Add a task and update its status
+    task_id = todo.add_task("Complete project", "Finish the bug bounty project")
+    todo.update_status(task_id, "completed")
+    
+    print(todo.list_tasks())
+    # Will show inconsistency: status="completed" but is_completed=False
\ No newline at end of file