public override string ToString()
        {
            int           bucket       = 0;
            StringBuilder hashTableStr = new StringBuilder();

            foreach (HashEntry entry in _data)
            {
                if (entry == null)
                {
                    continue;
                }
                hashTableStr.Append("\n bucket[")
                .Append(bucket)
                .Append("] = ")
                .Append(entry.ToString());
                bucket++;
                HashEntry temp = entry.Next;
                while (temp != null)
                {
                    hashTableStr.Append(" -> ");
                    hashTableStr.Append(temp.ToString());
                    temp = temp.Next;
                }
            }
            return(hashTableStr.ToString());
        }