code: def _get_encoding_opt(synchronizer, extra_opts, default):
      
      encoding = default
      # if synchronizer and "encoding" in synchronizer.options:
      #     encoding = synchronizer.options.get("encoding")
      if extra_opts and "encoding" in extra_opts:
          encoding = extra_opts.get("encoding")
      if encoding:
          # Normalize name (e.g. 'UTF8' => 'utf-8')
          encoding = codecs.lookup(encoding).name
      # print("_get_encoding_opt", encoding)
      return encoding or None
docs: Helper to figure out encoding setting inside constructors.