code: def set_headers(self) -> None:
          
          self.set_header("Accept-Ranges", "bytes")
          self.set_etag_header()
  
          if self.modified is not None:
              self.set_header("Last-Modified", self.modified)
  
          content_type = self.get_content_type()
          if content_type:
              self.set_header("Content-Type", content_type)
  
          cache_time = self.get_cache_time(self.path, self.modified, content_type)
          if cache_time > 0:
              self.set_header(
                  "Expires",
                  datetime.datetime.utcnow() + datetime.timedelta(seconds=cache_time),
              )
              self.set_header("Cache-Control", "max-age=" + str(cache_time))
  
          self.set_extra_headers(self.path)
docs: Sets the content and caching headers on the response.
  
          .. versionadded:: 3.1