code: def register_regex_entity(self, regex_str):
          
          if regex_str and regex_str not in self._regex_strings:
              self._regex_strings.add(regex_str)
              self.regular_expressions_entities.append(re.compile(regex_str, re.IGNORECASE))
docs: A regular expression making use of python named group expressions.
  
          Example: (?P<Artist>.*)
  
          regex_str(str): a string representing a regular expression as defined above