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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def lookup_future_symbol(self, symbol):
 """Lookup a future contract by symbol. Parameters symbol : str The symbol of the desired contract. Returns ------- future : Future The future contract referenced by ``symbol``. Raises ------ SymbolNotFound Raised when no contract named 'symbol' is found. """


        data = self._select_asset_by_symbol(self.futures_contracts, symbol)\
                   .execute().fetchone()

        # If no data found, raise an exception
        if not data:
            raise SymbolNotFound(symbol=symbol)
        return self.retrieve_asset(data['sid'])