code: def replace_simple_tags(s, from_tag='italic', to_tag='i', to_open_tag=None):
      
      if to_open_tag:
          s = s.replace('<' + from_tag + '>', to_open_tag)
      elif to_tag:
          s = s.replace('<' + from_tag + '>', '<' + to_tag + '>')
          s = s.replace('<' + from_tag + '/>', '<' + to_tag + '/>')
      else:
          s = s.replace('<' + from_tag + '>', '')
          s = s.replace('<' + from_tag + '/>', '')
  
      if to_tag:
          s = s.replace('</' + from_tag + '>', '</' + to_tag + '>')
      else:
          s = s.replace('</' + from_tag + '>', '')
  
      return s
docs: Replace tags such as <italic> to <i>
      This does not validate markup