code: def export_symbols(self):
          
          session = self.open_session()
          links = session.query(AssetClassStock).order_by(
              AssetClassStock.symbol).all()
          output = []
          for link in links:
              output.append(link.symbol + '\n')
  
          # Save output to a text file.
          with open("symbols.txt", mode='w') as file:
              file.writelines(output)
  
          print("Symbols exported to symbols.txt")
docs: Exports all used symbols