call (Merb::Rack::ConditionalGet)

    # File lib/merb-core/rack/middleware/conditional_get.rb, line 7
          def call(env)
            status, headers, body = @app.call(env)

            if document_not_modified?(env, headers)
              status = 304
              body = Merb::Const::EMPTY_STRING
              # set Date header using RFC1123 date format as specified by HTTP
              # RFC2616 section 3.3.1.
            end

            [status, headers, body]
          end