anchor.diff:    writeLine(int column, String text) {
       // Write any pending newlines.
       while (newlinesNeeded > 0) {
  -      buffer.add('\n');
  +      buffer.write('\n');
         newlinesNeeded--;
       }
   
  
positive.code: /** Pads [source] to [length] by adding spaces at the end. */
  String padRight(String source, int length) {
    final result = new StringBuffer();
    result.add(source);
  
    while (result.length < length) {
      result.add(' ');
    }
  
    return result.toString();
  }
negative.code:     // to the next line.
      while (currentColumn != column) {
        if (currentColumn < NUM_COLUMNS - 1) {
          buffer.write(padRight('', columnWidths[currentColumn]));
        } else {
          buffer.write('\n');
        }
        currentColumn = (currentColumn + 1) % NUM_COLUMNS;
      }
  
      if (column < columnWidths.length) {
        // Fixed-size column, so pad it.
        buffer.write(padRight(text, columnWidths[column]));
      } else {
        // The last column, so just write it.
        buffer.write(text);
      }
  
      // Advance to the next column.
  