code: def metadata_to_double_percent_options(metadata):
      
      options = []
      if 'cell_depth' in metadata:
          options.append('%' * metadata.pop('cell_depth'))
      if 'title' in metadata:
          options.append(metadata.pop('title'))
      if 'cell_type' in metadata:
          options.append('[{}]'.format(metadata.pop('cell_type')))
      metadata = metadata_to_json_options(metadata)
      if metadata != '{}':
          options.append(metadata)
      return ' '.join(options)
docs: Metadata to double percent lines