8 See also Mainland Sav. Ass'n v. Riverfront Assocs., Ltd., 872 F.2d 955, 956 (10th Cir.) (held that D'Oench Duhme barred obligor's defenses of intentional fraud, gross negligence, reckless conduct, breach of an agreement to fund, and breach of the implied covenant of contractual fair dealing because [n]othing in the note, accompanying security agreements or other documents pertaining to the tran