# File lib/jekyll_asset_pipeline/pipeline.rb, line 5
      def hash(source, manifest, options = {})
        options = DEFAULTS.merge(options)
        begin
          Digest::MD5.hexdigest(YAML::load(manifest).map! do |path|
            "#{path}#{File.mtime(File.join(source, path)).to_i}"
          end.join.concat(options.to_s))
        rescue Exception => e
          puts "Failed to generate hash from provided manifest."
          raise e
        end
      end