Bucket Storage & Basic Hashing

Start by implementing set(key, value) and get(key) over the initial bucket array.

The hash(key) method is provided to convert keys to a valid bucket index ($0 \le \text{index} < \text{capacity}$).

• set(key, value): Place the [key, value] pair into the appropriate bucket. If the key already exists in that bucket, update its value.
• get(key): Retrieve the value stored under key, or return null / None if not found.