    # File lib/rack/showstatus.rb, line 19
        def call(env)
          status, headers, body = @app.call(env)
          headers = Utils::HeaderHash.new(headers)
          empty = headers[CONTENT_LENGTH].to_i <= 0

          # client or server error, or explicit message
          if (status.to_i >= 400 && empty) || env["rack.showstatus.detail"]
            # This double assignment is to prevent an "unused variable" warning on
            # Ruby 1.9.3.  Yes, it is dumb, but I don't like Ruby yelling at me.
            req = req = Rack::Request.new(env)

            message = Rack::Utils::HTTP_STATUS_CODES[status.to_i] || status.to_s

            # This double assignment is to prevent an "unused variable" warning on
            # Ruby 1.9.3.  Yes, it is dumb, but I don't like Ruby yelling at me.
            detail = detail = env["rack.showstatus.detail"] || message

            body = @template.result(binding)
            size = Rack::Utils.bytesize(body)
            [status, headers.merge(CONTENT_TYPE => "text/html", CONTENT_LENGTH => size.to_s), [body]]
          else
            [status, headers, body]
          end
        end