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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 global_unlock_percent(self):
 """Global achievement unlock percent. :rtype: float """

        percent = CRef.cfloat()
        result = self._iface.get_ach_progress(self.name, percent)

        if not result:
            return 0.0

        return float(percent)