def default=(value)
      value = value.to_sym
      unless config.accounts.include?(value)
        raise NoSuchAccount
      end

      config[:default] = value
      config.save!
    end
def default=(value)
      value = value.to_sym
      unless config.accounts.include?(value)
        raise NoSuchAccount
      end

      config[:default] = value
      config.save!
    end
This is deliberately not abstracted (it could be easily accessed from
 withing the method_missing method, but that will just lead to nastiness
 later when I implement colors, for example.