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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 _validate_dtype(self, dtype):
 """ validate the passed dtype """


        if dtype is not None:
            dtype = pandas_dtype(dtype)

            # a compound dtype
            if dtype.kind == 'V':
                raise NotImplementedError("compound dtypes are not implemented"
                                          " in the {0} constructor"
                                          .format(self.__class__.__name__))

        return dtype