source: binary-improvements/AllocsCommands/PrivateMessageConnections.cs@ 325

using System.Collections.Generic;
using Steamworks;

namespace AllocsFixes.CustomCommands {
        public class PrivateMessageConnections {
                private static readonly Dictionary<CSteamID, CSteamID> senderOfLastPM = new Dictionary<CSteamID, CSteamID> ();

                public static void SetLastPMSender (ClientInfo _sender, ClientInfo _receiver) {
                        senderOfLastPM [_receiver.steamId] = _sender.steamId;
                }

                public static ClientInfo GetLastPMSenderForPlayer (ClientInfo _player) {
                        if (senderOfLastPM.ContainsKey (_player.steamId)) {
                                CSteamID recSteamId = senderOfLastPM [_player.steamId];
                                ClientInfo recInfo = ConnectionManager.Instance.Clients.ForSteamId (recSteamId);
                                return recInfo;
                        }

                        return null;
                }
        }
}