# File lib/fpm/package/gem.rb, line 47
  def input(gem)
    # 'arg'  is the name of the rubygem we should unpack.
    path_to_gem = download_if_necessary(gem, version)

    # Got a good gem now (downloaded or otherwise)
    #
    # 1. unpack it into staging_path
    # 2. take the metadata from it and update our wonderful package with it.
    load_package_info(path_to_gem)
    install_to_staging(path_to_gem)
  end