Holloway also makes two other specific complaints. First, he alleges that he was not informed of the maximum punishment he could receive as a result of the enhancement of his conviction for aggravated robbery. But aggravated robbery in Texas is a first-degree felony, Tex. Penal Code Ann. § 29.03(b); enhanced or unen-hanced, it is punishable by at most life or ninety-nine years in prison, id. §§ 12.32(a), 12.42(c). Thus, because Holloway knew of the maximum punishment for the unen-hanced offense he also knew of the maximum punishment for the enhanced offense. Second, Holloway alleges he was not informed that a “true” plea would waive his right to challenge the validity of the prior convictions in a subsequent collateral proceeding. See Zales v. Henderson, 433 F.2d 20, 24 (5th Cir.1970) (<HOLDING>). But there is no precedent for the proposition
holding that application of career offender enhancement falls within exception for prior convictions where facts are undisputed making it unnecessary for district court to engage in further fact finding about prior convictions holding that when a defendant stipulates to prior convictions in prosecutions for aggravated offenses under ndcc  390801 submission of prior convictions to a jury constitutes reversible error holding that when a defendant admits prior convictions at a habitual offender hearing he waives any complaints about the validity of the prior convictions holding our habitual offender act does not limit enhancement to prior felony convictions within a certain time holding that a defendant may challenge the validity of prior convictions during a sentencing hearing and that the burden to establish invalidity is on the challenging party