# File lib/automateit/package_manager.rb, line 97
  def _not_installed_helper?(*packages)
    _raise_unless_available

    # Requires that your PackageManager#installed? method is implemented.
    packages, opts = args_and_opts(*packages)
    packages = _list_normalizer(packages)
    packages = packages.keys if Hash === packages

    available = [installed?(packages, :details => true)].flatten
    missing = packages - available
    truth = (packages - missing).empty?
    result = opts[:details] ? [truth, missing] : truth
    log.debug(PNOTE+"not_installed?(#{packages.inspect}) => #{truth}: #{missing.inspect}")
    return result
  end