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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 disallowed_in_before_trading_start(exception):
 """ Decorator for API methods that cannot be called from within TradingAlgorithm.before_trading_start. `exception` will be raised if the method is called inside `before_trading_start`. Examples -------- @disallowed_in_before_trading_start(SomeException("Don't do that!")) def method(self):
 # Do stuff that is not allowed inside before_trading_start. """

    def decorator(method):
        @wraps(method)
        def wrapped_method(self, *args, **kwargs):
            if self._in_before_trading_start:
                raise exception
            return method(self, *args, **kwargs)
        return wrapped_method
    return decorator