discussed Cited "see, e.g." United States v. David P. Twomey However, this single comment, made in the course of a long and well-conducted trial, falls far short of reversible error, which will be found only if judicial intervention is substantial, United States v. Robinson, 687 F.2d 359, 361 (11th Cir.1982); see also United States v. Smith, 561 F.2d 8, 14 (6th Cir.1977), cert. denied, 434 U.S. 958 , 98 S.Ct. 487 , 54 L.Ed.2d 317 , 434 U.S. 972 , 98 S.Ct. 524 , 54 L.Ed.2d 461 (1977), 434 U.S. 1019 , 98 S.Ct. 741 , 54 L.Ed.2d 766 , 434 U.S. 1048 , 98 S.Ct. 897 , 54 L.Ed.2d 800 (1978), and interferes with a defendant’s right to a fair trial. 3 United St…