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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 merge(self, imgs):
 """Merge image channels. Parameters imgs : `list` of `PIL.Image.Image` Returns ------- `PIL.Image.Image` Raises ------ ValueError If image channel list is empty. """

        if not imgs:
            raise ValueError('empty channel list')
        if len(imgs) == 1:
            return imgs[0]
        return Image.merge(self.mode, imgs)