- is a collection of things
- allows duplicates
- isn't ordered but the items should be comparable
| Method | Effect |
|---|---|
| Bag() | Creates an empty bag |
| length() | Returns the number of items in the bag |
| contains(item) | Returns True if item is in the bag |
| add(item) | Adds item to the bag |
| remove(item) | Remove and return item from the bag or raise exception if it's not in the bag |
| iterator() | Create and return iterator to iterate over the bag |