code: def adjust_collateral_ratio(
          self, symbol, new_collateral_ratio, account=None, target_collateral_ratio=None
      ):
          
          if not account:
              if "default_account" in self.blockchain.config:
                  account = self.blockchain.config["default_account"]
          if not account:
              raise ValueError("You need to provide an account")
          account = Account(account, full=True, blockchain_instance=self.blockchain)
          current_debts = self.list_debt_positions(account)
          if symbol not in current_debts:
              raise ValueError(
                  "No Call position available to adjust! Please borrow first!"
              )
          return self.adjust_debt(
              Amount(0, symbol),
              new_collateral_ratio,
              account,
              target_collateral_ratio=target_collateral_ratio,
          )
docs: Adjust the collataral ratio of a debt position
  
              :param Asset amount: Amount to borrow (denoted in 'asset')
              :param float new_collateral_ratio: desired collateral ratio
              :param float target_collateral_ratio: Tag the call order so that in
                  case of margin call, only enough debt is covered to get back to
                  this ratio
              :raises ValueError: if symbol is not a bitasset
              :raises ValueError: if collateral ratio is smaller than maintenance collateral ratio
              :raises ValueError: if required amounts of collateral are not available