def cachedir
      if Gem.win_platform?
        File.join(ENV['LOCALAPPDATA'], 'PDK', 'cache')
      else
        File.join(Dir.home, '.pdk', 'cache')
      end
    end
def cachedir
      if Gem.win_platform?
        File.join(ENV['LOCALAPPDATA'], 'PDK', 'cache')
      else
        File.join(Dir.home, '.pdk', 'cache')
      end
    end
Returns the fully qualified path to a per-user PDK cachedir.

 @return [String] Fully qualified path to per-user PDK cachedir.