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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 field_pk_to_json(self, model, pk):
 """Convert a primary key to a JSON dict."""

        app_label = model._meta.app_label
        model_name = model._meta.model_name
        return {
            'app': app_label,
            'model': model_name,
            'pk': pk,
        }