code: def sanitize_http_headers(client, event):
      
      # request headers
      try:
          headers = event["context"]["request"]["headers"]
          event["context"]["request"]["headers"] = varmap(_sanitize, headers)
      except (KeyError, TypeError):
          pass
  
      # response headers
      try:
          headers = event["context"]["response"]["headers"]
          event["context"]["response"]["headers"] = varmap(_sanitize, headers)
      except (KeyError, TypeError):
          pass
  
      return event
docs: Sanitizes http request/response headers
  
      :param client: an ElasticAPM client
      :param event: a transaction or error event
      :return: The modified event