/// <summary>Get or add a coin by symbol name</summary>
 public Coin GetOrAdd(string sym)
 {
     Debug.Assert(Misc.AssertMainThread());
     Debug.Assert(m_coin_data.IndexOf(x => x.Symbol == sym) != -1, "Don't add coins that are not in the settings");
     return(Coins.GetOrAdd(sym, CreateCoin));
 }