Can a defendant waiver the right to appeal a sentence that has yet been imposed?

Sentencing, however, does not occur contemporaneously with the plea and waiver. It is a future event, and the mistakes from which one might have reason to appeal have not yet occurred at the time a defendant waives the right to appeal or collaterally attack the plea or sentencing proceedings. A defendant cannot know what he or she has given up by waiving the right to appeal until after the judge and counsel have reviewed a yet-to-be-prepared presentence investigation report, after the judge has considered other information not known to the defendant at the time of the plea, and after the judge has actually imposed sentence. By then it is too late, no matter how disproportionate the sentence or how egregious the procedural or substantive errors committed by the sentencing judge or the defendant's own counsel. It is hard to see how a defendant at the plea hearing can ever knowingly and intelligentlythat is, with a full awareness of both the nature of the right [s] being abandoned and the consequences of the decision to abandon it, Moran v. Burbine,475 U.S. 412, 422, 106 S.Ct. 1135, 89 L.Ed.2d 410 (1986)waive the right to appeal or collaterally attack a sentence that has not yet been imposed. Such prospective waivers in anticipation of unknown future events are inherently unknowing and unintelligent.⁴