discussed Cited "see, e.g." United States v. Charles See United States v. Machor, 879 F.2d 945 , 953 & n. 2 (1st Cir.1989) (rejecting defendants’ argument that court abused its discretion in not sequestering the government’s case agent because “[t]he majority view ... is that Fed.R.Evid. 615(2) has severely cur *258 tailed the discretion of the trial court to sequester the government’s case agent,” but noting that “[w]e are not holding ... that the rule withdraws all discretion from the trial court to exclude a case agent in an exceptional case”) (citations omitted); see also United States v. Casas, 356 F.3d 104, 126 (1st Cir.) (no…