Signature Bank figured it was entitled to grab $300,000 from James M. Cassidy’s individual retirement accounts when a company he owned defaulted on $3.5 million in loans — even though Section 12-1006(a) of the Illinois Code of Civil Procedure exempts IRAs from “seizure for the satisfaction of debts” — because (1) Cassidy signed “assignment of deposit account” agreements that gave the bank security interests in the IRAs and (2) Section 408(e)(4) of the Internal Revenue Code says any portion of an IRA that is used as …