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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 modify(self, symbol, base_value):
 """ Change the base value of a unit symbol. Useful for adjusting code units after parsing parameters. Parameters symbol : str The name of the symbol to modify base_value : float The new base_value for the symbol. """

        self._unit_system_id = None

        if symbol not in self.lut:
            raise SymbolNotFoundError(
                "Tried to modify the symbol '%s', but it does not exist "
                "in this registry." % symbol
            )

        if hasattr(base_value, "in_base"):
            new_dimensions = base_value.units.dimensions
            base_value = base_value.in_base("mks")
            base_value = base_value.value
        else:
            new_dimensions = self.lut[symbol][1]

        self.lut[symbol] = (float(base_value), new_dimensions) + self.lut[symbol][2:]