docs: def join_content_version(self, to_cache):
          """
          Add the version(s) to the content to cache : internal version at first
          and then the template version if versioning is activated.
          Each version, and the content, are separated with `VERSION_SEPARATOR`.
          This method is called after the encoding (if "compress" or
          "compress_spaces" options are on)
          """
          parts = [self.INTERNAL_VERSION]
          if self.options.versioning:
              parts.append(force_bytes(self.version))
          parts.append(force_bytes(to_cache))
  
          return self.VERSION_SEPARATOR.join(parts)