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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 _create_execution_context(self):
 """instantiates the internal query execution context based. """

        if hasattr(self, '_database_link'):
            # client side partitioning query
            return base_execution_context._MultiCollectionQueryExecutionContext(self._client, self._options, self._database_link, self._query, self._partition_key)
        else:
            # 
            return execution_dispatcher._ProxyQueryExecutionContext(self._client, self._collection_link, self._query, self._options, self._fetch_function)