Converted enough to send the system card

Myriad/Extensions/CacheExtensions.cs

@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+
+using Myriad.Cache;
+using Myriad.Types;
+
+namespace Myriad.Extensions
+{
+    public static class CacheExtensions
+    {
+        public static Guild GetGuild(this IDiscordCache cache, ulong guildId)
+        {
+            if (!cache.TryGetGuild(guildId, out var guild))
+                throw new KeyNotFoundException($"Guild {guildId} not found in cache");
+            return guild;
+        }
+        
+        public static Channel GetChannel(this IDiscordCache cache, ulong channelId)
+        {
+            if (!cache.TryGetChannel(channelId, out var channel))
+                throw new KeyNotFoundException($"Channel {channelId} not found in cache");
+            return channel;
+        }
+
+        public static Channel? GetChannelOrNull(this IDiscordCache cache, ulong channelId)
+        {
+            if (cache.TryGetChannel(channelId, out var channel))
+                return channel;
+            return null;
+        }
+
+        public static User GetUser(this IDiscordCache cache, ulong userId)
+        {
+            if (!cache.TryGetUser(userId, out var user))
+                throw new KeyNotFoundException($"User {userId} not found in cache");
+            return user;
+        }
+        
+        public static Role GetRole(this IDiscordCache cache, ulong roleId)
+        {
+            if (!cache.TryGetRole(roleId, out var role))
+                throw new KeyNotFoundException($"User {roleId} not found in cache");
+            return role;
+        }
+    }
+}