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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 __get_default_currency(self):
 """Read the default currency from GnuCash preferences"""

        # If we are on Windows, read from registry.
        if sys.platform == "win32":
            # read from registry
            def_curr = self.book["default-currency"] = self.__get_default_currency_windows()
        else:
            # return the currency from locale.
            # todo: Read the preferences on other operating systems.
            def_curr = self.book["default-currency"] = self.__get_locale_currency()

        return def_curr