Handle Unique Elements and Set Operations with Python Sets

# Example 1: Finding unique user IDs from a list of logs
request_user_ids = [101, 203, 101, 405, 203, 506, 101]
unique_users = set(request_user_ids)
print(f"Unique users: {unique_users}") # Output: {101, 203, 405, 506}

# Example 2: Fast membership testing (e.g., checking if a user is online)
online_users = {101, 304, 506, 708}
user_id_to_check = 203
if user_id_to_check in online_users:
    print(f"User {user_id_to_check} is online.")
else:
    print(f"User {user_id_to_check} is offline.") # Output: User 203 is offline.

# Example 3: Finding users who viewed product A but not product B (set difference)
viewed_product_a = {101, 203, 405, 809}
viewed_product_b = {101, 506, 809, 910}
viewed_a_only = viewed_product_a - viewed_product_b
print(f"Users who viewed A but not B: {viewed_a_only}") # Output: {203, 405}

# Example 4: Finding users who viewed both products (set intersection)
viewed_both = viewed_product_a.intersection(viewed_product_b)
print(f"Users who viewed both A and B: {viewed_both}") # Output: {101, 809}