In Heimstadt v. Tapered Parts, Inc. (1957) 155 Cal.App.2d 711, the parties entered into a contract that provided: "'Should an attorney be employed to procure payment hereof by suit or otherwise, the undersigned, jointly and severally, agree to pay a reasonable sum as attorney's fees therefor.'" (Heimstadt v. Tapered Parts, Inc., supra, 155 Cal.App.2d at p. 712.) Prior to the plaintiff filing a lawsuit, the defendant offered payment of an amount that did not include the $300 the plaintiff claimed was the reasonable amount of attorney fees incurred as a result of the defendant's breach of the contract. (Id. at pp. 712-713.) It was in this context that the court stated, "It cannot be seriously maintained that an obligation which includes a liability for attorney's fees can be satisfied by the payment of the sum exclusive of attorney's fees." (Id. at p. 714.) The court continued: "When the obligation to pay such a charge has accrued it becomes a part of the principal obligation. A creditor to whom payment is due has no duty to accept less than the entire debt." (Ibid.)