text: def main(request, response):
      tag = request.GET.first(b"tag", None)
      match = request.headers.get(b"If-None-Match", None)
      date = request.GET.first(b"date", b"")
      modified = request.headers.get(b"If-Modified-Since", None)
      cors = request.GET.first(b"cors", None)
  
      if request.method == u"OPTIONS":
          response.headers.set(b"Access-Control-Allow-Origin", b"*")
          response.headers.set(b"Access-Control-Allow-Headers", b"IF-NONE-MATCH")
          return b""
  
      if tag:
          response.headers.set(b"ETag", b'"%s"' % tag)
      elif date:
          response.headers.set(b"Last-Modified", date)
  
      if cors:
          response.headers.set(b"Access-Control-Allow-Origin", b"*")
  
      if ((match is not None and match == tag) or
              (modified is not None and modified == date)):
          response.status = (304, b"SUPERCOOL")
          return b""
      else:
          if not cors:
              response.headers.set(b"Access-Control-Allow-Origin", b"*")
          response.headers.set(b"Content-Type", b"text/plain")
          return b"MAYBE NOT"
  