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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 with_preference_param(self):
 """Add the preference param to the ES request and return a new Search. The preference param avoids the bouncing effect with multiple replicas, documented on ES documentation. See: https://www.elastic.co/guide/en/elasticsearch/guide/current /_search_options.html#_preference for more information. """

        user_hash = self._get_user_hash()
        if user_hash:
            return self.params(preference=user_hash)
        return self