def SetBalanceFor(self, assetId, fixed8_val):
        """
        Set the balance for an asset id.
        Args:
            assetId (UInt256):
            fixed8_val (Fixed8): balance value.
        """
        found = False
        for key, val in self.Balances.items():
            if key == assetId:
                self.Balances[key] = fixed8_val
                found = True

        if not found:
            self.Balances[assetId] = fixed8_val