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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_public_comments_for_model(model):
 """ Get visible comments for the model. """

    if not IS_INSTALLED:
        # No local comments, return empty queryset.
        # The project might be using DISQUS or Facebook comments instead.
        return CommentModelStub.objects.none()
    else:
        return CommentModel.objects.for_model(model).filter(is_public=True, is_removed=False)