(a) Preference of creditors in general assignments of all a debtor's property for the benefit of creditors shall be illegal and voidable, and all general assignments shall operate for the benefit of all the debtor's creditors pro rata, whether all the creditors are named in the assignment or not.
(b) The insertion of a clause in the assignment giving a preference shall not render the assignment itself invalid, but the clause only shall be nugatory, and all the debtor's creditors shall share ratably in property assigned.