code: public void registerCommandHandler (MessageBundle msg, String command, CommandHandler handler)
      {
          // the usage key is derived from the untranslated command
          handler._usageKey = "m.usage_" + command;
  
          String key = "c." + command;
          handler._aliases = msg.exists(key) ? msg.get(key).split("\\s+") : new String[] { command };
          for (String alias : handler._aliases) {
              _handlers.put(alias, handler);
          }
      }
docs: Registers a chat command handler.
  
  @param msg the message bundle via which the slash command will be translated (as
  <code>c.</code><i>command</i>). If no translation exists the command will be
  <code>/</code><i>command</i>.
  @param command the name of the command that will be used to invoke this handler (e.g.
  <code>tell</code> if the command will be invoked as <code>/tell</code>).
  @param handler the chat command handler itself.