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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 Add(self, category, label, age):
 """Adds another instance of this category into the active_days counter. We automatically count the event towards all relevant active_days. For example, if the category "Windows" was seen 8 days ago it will be counted towards the 30 day active, 14 day active but not against the 7 and 1 day actives. Args: category: The category name to account this instance against. label: Client label to which this should be applied. age: When this instance occurred. """

    now = rdfvalue.RDFDatetime.Now()
    category = utils.SmartUnicode(category)

    for active_time in self.active_days:
      self.categories[active_time].setdefault(label, {})
      if (now - age).seconds < active_time * 24 * 60 * 60:
        self.categories[active_time][label][
            category] = self.categories[active_time][label].get(category, 0) + 1