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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_table(self, model_class):
        '''
        Creates a table for the given model class, if it does not exist already.
        '''
        if model_class.is_system_model():
            raise DatabaseException("You can't create system table")
        if getattr(model_class, 'engine') is None:
            raise DatabaseException("%s class must define an engine" % model_class.__name__)
        self._send(model_class.create_table_sql(self))