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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 tally(self, name, value):
 """Adds to the "used" metric for the given quota."""

        value = value or 0  # Protection against None.
        # Start at 0 if this is the first value.
        if 'used' not in self.usages[name]:
            self.usages[name]['used'] = 0
        # Increment our usage and update the "available" metric.
        self.usages[name]['used'] += int(value)  # Fail if can't coerce to int.
        self.update_available(name)