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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 get_bmus(self, activation_map):
 """Returns Best Matching Units indexes of the activation map. :param activation_map: Activation map computed with self.get_surface_state() :type activation_map: 2D numpy.array :returns: The bmus indexes corresponding to this activation map (same as self.bmus for the training samples). :rtype: 2D numpy.array """


        Y, X = np.unravel_index(activation_map.argmin(axis=1),
                                (self._n_rows, self._n_columns))
        return np.vstack((X, Y)).T