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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 add(self, index, var):
 """Add a minibatch of images to the monitor. Args: index (int):
 Index. var (:obj:`~nnabla.Variable`, :obj:`~nnabla.NdArray`, or :obj:`~numpy.ndarray`):
 If C == 2, blue channel is appended with ones. If C > 3, the array will be sliced to remove C > 3 sub-array. """

        import nnabla as nn
        from nnabla.utils.image_utils import imsave
        if index != 0 and (index + 1) % self.interval != 0:
            return
        if isinstance(var, nn.Variable):
            data = var.d.copy()
        elif isinstance(var, nn.NdArray):
            data = var.data.copy()
        else:
            assert isinstance(var, np.ndarray)
            data = var.copy()
        assert data.ndim > 2
        channels = data.shape[-3]
        data = data.reshape(-1, *data.shape[-3:])
        data = data[:min(data.shape[0], self.num_images)]
        data = self.normalize_method(data)
        if channels > 3:
            data = data[:, :3]
        elif channels == 2:
            data = np.concatenate(
                [data, np.ones((data.shape[0], 1) + data.shape[-2:])], axis=1)
        path_tmpl = os.path.join(self.save_dir, '{:06d}-{}.png')
        for j in range(min(self.num_images, data.shape[0])):
            img = data[j].transpose(1, 2, 0)
            if img.shape[-1] == 1:
                img = img[..., 0]
            path = path_tmpl.format(index, '{:03d}'.format(j))
            imsave(path, img)
        if self.verbose:
            logger.info("iter={} {{{}}} are written to {}.".format(
                index, self.name, path_tmpl.format(index, '*')))