code: def once_parser(cards: list) -> Optional[list]:
      '''
      parser for ONCE [2] issue mode
      Only one issuance transaction from asset owner allowed.
      '''
  
      first_issue = next(i for i in cards if i.type == "CardIssue")  # find first CardIssue
  
      filtered = [i for i in cards if i.type == "CardIssue" if i != first_issue]  #  drop all other CardIssues
  
      return [i for i in cards if i not in filteredf once_parser(cards: list) -> Optional[list]:
      '''
      parser for ONCE [2] issue mode
      Only one issuance transaction from asset owner allowed.
      '''
  
      first_issue = next(i for i in cards if i.type == "CardIssue")  # find first CardIssue
  
      filtered = [i for i in cards if i.type == "CardIssue" if i != first_issue]  #  drop all other CardIssues
  
      return [i for i in cards if i not in filtered]
docs: parser for ONCE [2] issue mode
      Only one issuance transaction from asset owner allowed.