AL REPORTER, 2d SERIES U.S. 267, 92 S.Ct 496, 30 LEd.2d 427 (1971) (plea agreement); In re Arnett, 804 F.2d 1200 (1111 Cw.1986) (plea agreement); Rowe v. Griffin, 676 F.2d 624 (11th Cir. 1982) (immunity) United States v. Weiss, 599 F.2d 780, 737 (6th Cir.1979) (immunity) (Tuttle, J.) ('lle protect the volun