<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def cost(self):
 """Get the approximate cost of this filter. Cost is the total cost of the exclusion rules in this filter. The cost of family-specific filters is divided by 10. Returns: float: The approximate cost of the filter. """

        total = 0.0
        for family, rules in self._excludes.iteritems():
            cost = sum(x.cost() for x in rules)
            if family:
                cost = cost / float(10)
            total += cost
        return total