code: def _diff_group_position(group):
      
      old_start = group[0][0]
      new_start = group[0][1]
      old_length = new_length = 0
      for old_line, new_line, line_or_conflict in group:
          if isinstance(line_or_conflict, tuple):
              old, new = line_or_conflict
              old_length += len(old)
              new_length += len(new)
          else:
              old_length += 1
              new_length += 1
      if old_length:
          old_start += 1
      if new_length:
          new_start += 1
  
      return color.LineNumber('@@ -%s,%s +%s,%s @@' % (old_start, old_length, new_start, new_length))
docs: Generate a unified diff position line for a diff group