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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 _process_params(self):
 """ Adds default row size if it's not given in the query. Converts param values into unicode strings. Returns: Processed self._solr_params dict. """

        # transform sort dict into str
        self._sort_to_str()

        if 'rows' not in self._solr_params:
            self._solr_params['rows'] = self._cfg['row_size']

        for key, val in self._solr_params.items():
            if isinstance(val, str) and six.PY2:
                self._solr_params[key] = val.encode(encoding='UTF-8')
        return self._solr_params