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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_permission_required(cls):
 """ Get permission required property. Must return an iterable. """

        if cls.permission_required is None:
            raise ImproperlyConfigured(
                "{0} is missing the permission_required attribute. "
                "Define {0}.permission_required, or override "
                "{0}.get_permission_required().".format(cls.__name__)
            )
        if isinstance(cls.permission_required, six.string_types):
            if cls.permission_required != "":
                perms = (cls.permission_required,)
            else:
                perms = ()
        else:
            perms = cls.permission_required

        return perms