code: def summarize_attr(key, value, col_width=None):
      
      # Indent key and add ':', then right-pad if col_width is not None
      k_str = '    {}:'.format(key)
      if col_width is not None:
          k_str = pretty_print(k_str, col_width)
      # Replace tabs and newlines, so we print on one line in known width
      v_str = str(value).replace('\t', '\\t').replace('\n', '\\n')
      # Finally, truncate to the desired display width
      return maybe_truncate('{} {}'.format(k_str, v_str),
                            OPTIONS['display_width'])
docs: Summary for __repr__ - use ``X.attrs[key]`` for full value.