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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, filter_key, operator, value):
 """ Adds a filter given a key, operator, and value"""

        filter_key = self._metadata_map.get(filter_key, filter_key)
        self.filters.append({'filter': filter_key, 'operator': operator, 'value': value})