code: function defaultHandler(command) {
          debug(`executing default handler for unrecognized command ${command.commandText}`);
          if (!command.mention) {
              command.reply(`Command \`${command.command}\` is not recognized`);
          }
          return Promise.resolve();
      }
docs: Default Handler for unknown commands
  
  Post an error reply only if command is not a mention command
  
  @private
  
  @param {Command} command Unknown Command
  @returns {Promise} Resolves after action is taken