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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 post_migrate(cls, sender=None, **kwargs):
 """ Iterate over fake_proxy_models and add contenttypes and permissions for missing proxy models, if this has not been done by Django yet """

        ContentType = apps.get_model('contenttypes', 'ContentType')

        for model_name, proxy_model in sender.get_proxy_models().items():
            ctype, created = ContentType.objects.get_or_create(app_label=sender.label, model=model_name)
            if created:
                sender.grant_permissions(proxy_model)