public Dictionary<string, List<Card>> GetDictionary()
            {
                return _deck.GroupBy(c => c.Suit).ToDictionary(g => g.Key, g => g.ToList());
            }

            public override string ToString()
            {
                var dict = GetDictionary();

                StringBuilder sb = new StringBuilder();
                sb.Append(string.Format("{0}\t{1}\t{2}\t{3}\n" +
                    "================================\n",
                        _suits[0],
                        _suits[1],
                        _suits[2],
                        _suits[3]));

                for(int i = 0; i < _deck.Count / _suits.Count; ++i)
                {
                    sb.Append(string.Format("{0}\t{1}\t{2}\t{3}\n",
                        dict["Hearts"][i].Face,
                        dict["Clubs"][i].Face,
                        dict["Spades"][i].Face,
                        dict["Diamonds"][i].Face));
                }

                return sb.ToString();
            }