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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_filter(self, key, filter_value):
 """ add and validate a filter with value returns True on success otherwise exception """

        seek = u"filter[%s]" % key
        if self.validate_filter(key, filter_value):
            self.filters[key] = filter_value
            return True
        else:
            msg = u'Invalid filter value: filter:%s value:%s' % (key, filter_value)
            print msg
            raise SalesKingException("FILTER_INVALID", msg )