call (Rack::Chunked)

    # File lib/rack/chunked.rb, line 14
        def call(env)
          status, headers, body = @app.call(env)
          headers = HeaderHash.new(headers)

          if env['HTTP_VERSION'] == 'HTTP/1.0' ||
             STATUS_WITH_NO_ENTITY_BODY.include?(status) ||
             headers['Content-Length'] ||
             headers['Transfer-Encoding']
            [status, headers.to_hash, body]
          else
            dup.chunk(status, headers, body)
          end
        end