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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 type(self) -> str: """ One of `'single'` or `'multi'`. """

        model = self.name
        if 'single' in model:
            return 'single'
        elif 'multi' in model:
            return 'multi'
        else:
            raise RuntimeError("Bad pipette model name: {}".format(model))