In Schulze & Burch Biscuit Co. v. Tree Top, Inc., 831 F.2d 709 (7th Cir.1987), the Seventh Circuit noted that Illinois's version of U.C.C. 2-207 is followed by official comments suggesting that proposed terms consistent with trade practice or custom do not materially alter a contract. Id. at 714. In that case, Tree Top was seeking to enforce an arbitration clause contained in a written confirmation. The Seventh Circuit held that the arbitration clause did not constitute a material alteration of the parties' contract, because although Tree Top did not offer proof of a trade usage, it did prove a course of dealing between the parties that should have put Schulze on notice that the confirmation was likely to contain such a clause. Id. at 714-15.