Whether a district court has a duty to determine on its own whether the Bureau of Prisons will give credit for presentence detention time when a defendant requests such credit

Question Presented 1. If a defendant requests that he be given credit towards his federal sentence for presentence detention time, is a district court — knowing that the court cannot actually give “credit” — thereby put on notice that the court has a duty to determine on its own whether or not the Bureau of Prisons will give credit for presentence detention time, and adjust the defendant’s sentence accordingly? i