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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 update_contributions(sender, instance, action, model, pk_set, **kwargs):
 """Creates a contribution for each author added to an article. """

    if action != 'pre_add':
        return
    else:
        for author in model.objects.filter(pk__in=pk_set):
            update_content_contributions(instance, author)