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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_group(images):
 """Validates that the combination of folder and name for all images in a group is unique. Raises a ValueError exception if uniqueness constraint is violated. Parameters images : List(GroupImage) List of images in group """

        image_ids = set()
        for image in images:
            key = image.folder + image.name
            if key in image_ids:
                raise ValueError('Duplicate images in group: ' + key)
            else:
                image_ids.add(key)