text: import os
  import uuid
  import hashlib
  import time
  import json
  
  def main(request, response):
    ## Get the query parameter (key) from URL ##
    ## Tests will record POST requests (CSP Report) and GET (rest) ##
    if request.GET:
      key = request.GET['file']
    elif request.POST:
      key = request.POST['file']
  
    ## Convert the key from String to UUID valid String ##
    testId = hashlib.md5(key).hexdigest()
  
    ## Handle the header retrieval request ##
    if 'retrieve' in request.GET:
      response.writer.write_status(200)
      response.writer.end_headers()
      try:
        header_value = request.server.stash.take(testId)
        response.writer.write(header_value)
      except (KeyError, ValueError) as e:
        response.writer.write("No header has been recorded")
        pass
  
      response.close_connection = True
  
    ## Record incoming fetch metadata header value
    else:
      try:
        ## Return a serialized JSON object with one member per header. If the ##
        ## header isn't present, the member will contain an empty string.     ##
        header = json.dumps({
          "dest": request.headers.get("sec-fetch-dest", ""),
          "mode": request.headers.get("sec-fetch-mode", ""),
          "site": request.headers.get("sec-fetch-site", ""),
          "user": request.headers.get("sec-fetch-user", ""),
        })
        request.server.stash.put(testId, header)
      except KeyError:
        ## The header is already recorded or it doesn't exist
        pass
  
      ## Prevent the browser from caching returned responses and allow CORS ##
      response.headers.set("Access-Control-Allow-Origin", "*")
      response.headers.set("Cache-Control", "no-cache, no-store, must-revalidate")
      response.headers.set("Pragma", "no-cache")
      response.headers.set("Expires", "0")
  
      ## Add a valid ServiceWorker Content-Type ##
      if key.startswith("serviceworker"):
        response.headers.set("Content-Type", "application/javascript")
  
      ## Add a valid image Content-Type ##
      if key.startswith("image"):
        response.headers.set("Content-Type", "image/png")
        file = open(os.path.join(request.doc_root, "media", "1x1-green.png"), "r")
        image = file.read()
        file.close()
        return image
  
      ## Return a valid .vtt content for the <track> tag ##
      if key.startswith("track"):
        return "WEBVTT"
  
      ## Return a valid SharedWorker ##
      if key.startswith("sharedworker"):
        response.headers.set("Content-Type", "application/javascript")
        file = open(os.path.join(request.doc_root, "fetch", "metadata",
                                 "resources", "sharedWorker.js"), "r")
        shared_worker = file.read()
        file.close()
        return shared_worker
  
      ## Return a valid font content and Content-Type ##
      if key.startswith("font"):
        response.headers.set("Content-Type", "application/x-font-ttf")
        file = open(os.path.join(request.doc_root, "fonts", "Ahem.ttf"), "r")
        font = file.read()
        file.close()
        return font
  
      ## Return a valid audio content and Content-Type ##
      if key.startswith("audio"):
        response.headers.set("Content-Type", "audio/mpeg")
        file = open(os.path.join(request.doc_root, "media", "sound_5.mp3"), "r")
        audio = file.read()
        file.close()
        return audio
  
      ## Return a valid video content and Content-Type ##
      if key.startswith("video"):
        response.headers.set("Content-Type", "video/mp4")
        file = open(os.path.join(request.doc_root, "media", "A4.mp4"), "r")
        video = file.read()
        file.close()
        return video
  
      ## Return a valid style content and Content-Type ##
      if key.startswith("style") or key.startswith("embed") or key.startswith("object"):
        response.headers.set("Content-Type", "text/html")
        return "<html>EMBED!</html>"
  
      ## Return a valid image content and Content-Type for redirect requests ##
      if key.startswith("redirect"):
        response.headers.set("Content-Type", "image/jpeg")
        file = open(os.path.join(request.doc_root, "media", "1x1-green.png"), "r")
        image = file.read()
        file.close()
        return image
  
      ## Return a valid dedicated worker
      if key.startswith("worker"):
        response.headers.set("Content-Type", "application/javascript")
        return "self.postMessage('loaded');"
  
      ## Return a valid XSLT
      if key.startswith("xslt"):
        response.headers.set("Content-Type", "text/xsl")
        return """<?xml version="1.0" encoding="UTF-8"?>
  <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:template match="@*|node()">
      <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
      </xsl:copy>
    </xsl:template>
  </xsl:stylesheet>"""
  
  