buildERC721TransactionEndpoint method 
    
    
    
  Implementation
  String buildERC721TransactionEndpoint({
  required String address,
  String? contractAddress,
  int? startblock,
  int? endblock,
  int? page,
  int? offset,
  Sorting? sorting,
}) =>
    "$base&module=account&action=tokennfttx&address=$address"
        .addOptionalParameter('contractaddress', contractAddress)
        .addOptionalParameter('startblock', startblock)
        .addOptionalParameter('endblock', endblock)
        .addOptionalParameter('page', page)
        .addOptionalParameter('offset', offset)
        .addOptionalParameter('sort', sorting?.name);