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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 _extract_lookup(self, key):
 """Extract lookup method based on key name format"""

        parts = key.split('__')
        # 'exact' is the default lookup if there was no explicit comparison op in `key`
        #   Assume there is only one `__` in the key.
        #   FIXME Change for child attribute query support
        op = 'exact' if len(parts) == 1 else parts[1]

        # Construct and assign the lookup class as a filter criteria
        return parts[0], self.get_lookup(op)