def latest_specs(include_prerelease=false)
    result = Hash.new { |h,k| h[k] = [] }
    latest = {}

    sort.each do |_, spec|
      name = spec.name
      curr_ver = spec.version
      prev_ver = latest.key?(name) ? latest[name].version : nil

      next if !include_prerelease && curr_ver.prerelease?
      next unless prev_ver.nil? or curr_ver >= prev_ver or
                  latest[name].platform != Gem::Platform::RUBY

      if prev_ver.nil? or
         (curr_ver > prev_ver and spec.platform == Gem::Platform::RUBY) then
        result[name].clear
        latest[name] = spec
      end

      if spec.platform != Gem::Platform::RUBY then
        result[name].delete_if do |result_spec|
          result_spec.platform == spec.platform
        end
      end

      result[name] << spec
    end

    result.values.flatten
  end
#
Returns an Array specifications for the latest released versions
of each gem in this index.