code: def update_cer(self, symbol, cer, account=None):
          
          assert isinstance(
              cer, Price
          ), "cer needs to be instance of `bitshares.price.Price`!"
          if not account:
              if "default_account" in self.config:
                  account = self.config["default_account"]
          if not account:
              raise ValueError("You need to provide an account")
          account = Account(account, blockchain_instance=self)
          asset = Asset(symbol, blockchain_instance=self, full=True)
          assert (
              asset["id"] == cer["base"]["asset"]["id"]
              or asset["id"] == cer["quote"]["asset"]["id"]
          ), "Price needs to contain the asset of the symbol you'd like to produce a feed for!"
  
          cer = cer.as_base(symbol)
          if cer["quote"]["asset"]["id"] != "1.3.0":
              raise ValueError("CER must be defined against core asset '1.3.0'")
  
          options = asset["options"]
          options.update({"core_exchange_rate": cer.as_base(symbol).json()})
          op = operations.Asset_update(
              **{
                  "fee": {"amount": 0, "asset_id": "1.3.0"},
                  "issuer": account["id"],
                  "asset_to_update": asset["id"],
                  "new_options": options,
                  "extensions": [],
                  "prefix": self.prefix,
              }
          )
          return self.finalizeOp(op, account["name"], "active")
docs: Update the Core Exchange Rate (CER) of an asset
  
              :param str symbol: Symbol of the asset to publish feed for
              :param bitshares.price.Price cer: Core exchange Rate
              :param str account: (optional) the account to allow access
                  to (defaults to ``default_account``)