code: def fix_re_escapes(self, txt: str) -> str:
          
          def _subf(matchobj):
              # o = self.fix_text_escapes(matchobj.group(0))
              o = matchobj.group(0).translate(self.re_trans_table)
              if o[1] in '\b\f\n\t\r':
                  return o[0] + 'bfntr'['\b\f\n\t\r'.index(o[1])]
              else:
                  return o if o[1] in '\\.?*+^$()[]{|}' else o[1]
  
          return re.sub(r'\\.', _subf, txt, flags=re.MULTILINE + re.DOTALL + re.UNICODE)
docs: The ShEx RE engine allows escaping any character.  We have to remove that escape for everything except those
          that CAN be legitimately escaped
  
          :param txt: text to be escaped