code: def split_emails(msg):
      
      msg_body = _replace_link_brackets(msg)
  
      # don't process too long messages
      lines = msg_body.splitlines()[:MAX_LINES_COUNT]
      markers = remove_initial_spaces_and_mark_message_lines(lines)
  
      markers = _mark_quoted_email_splitlines(markers, lines)
  
      # we don't want splitlines in header blocks
      markers = _correct_splitlines_in_headers(markers, lines)
  
      return markers
docs: Given a message (which may consist of an email conversation thread with
      multiple emails), mark the lines to identify split lines, content lines and
      empty lines.
  
      Correct the split line markers inside header blocks. Header blocks are
      identified by the regular expression RE_HEADER.
  
      Return the corrected markers