code: protected final Bucket<K, V> getBucketForKey(K key) {
          int bucket_index = (key.hashCode() & 0x7FFFFFFF) % buckets.length;
          Bucket<K, V> thebucket = buckets[bucket_index];
          if (thebucket == null) {
              synchronized (this) {
                  thebucket = buckets[bucket_index];
                  if (thebucket == null) {
                      thebucket = new Bucket<K, V>();
                      buckets[bucket_index] = thebucket;
                  } // if
              } // sync
          } // if
          return thebucket;
      }
docs: Returns the bucket which the specified key hashes to