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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 convert_value(self, value):
 """Convert value to float. If value is a string, ensure that the first character is the same as symbol ie. the value is in the currency this formatter is representing. """

        if isinstance(value, str):
            assert value.startswith(self.symbol), "Currency does not start with " + self.symbol
            value = value.lstrip(self.symbol)
        return super().convert_value(value)