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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 _datetime64_index(self, recarr):
 """ Given a np.recarray find the first datetime64 column """

        # TODO: Handle multi-indexes
        names = recarr.dtype.names
        for name in names:
            if recarr[name].dtype == DTN64_DTYPE:
                return name
        return None