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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 _register_admin(admin_site, model, admin_class):
 """ Register model in the admin, ignoring any previously registered models. Alternatively it could be used in the future to replace a previously registered model. """

    try:
        admin_site.register(model, admin_class)
    except admin.sites.AlreadyRegistered:
        pass