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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 sensor_names(self):
 """Return standard sensor or instrument name for the file's data. """

        res = self['/attr/instrument_name']
        if isinstance(res, np.ndarray):
            res = str(res.astype(str))
        res = [x.strip() for x in res.split(',')]
        if len(res) == 1:
            return res[0]
        return res