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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_role_model():
 """ Returns the Role model that is active in this project. """

    app_model = getattr(settings, "ARCTIC_ROLE_MODEL", "arctic.Role")

    try:
        return django_apps.get_model(app_model)
    except ValueError:
        raise ImproperlyConfigured(
            "ARCTIC_ROLE_MODEL must be of the " "form 'app_label.model_name'"
        )
    except LookupError:
        raise ImproperlyConfigured(
            "ARCTIC_ROLE_MODEL refers to model '%s' that has not been "
            "installed" % settings.ARCTIC_ROLE_MODEL
        )