What is the test for establishing that a conspiracy has been terminated or terminated?

4 See also United States v. Katz, 601 F.2d 66, 68 (2d Cir.1979) ("Appellants seem to [argue] that after the coconspirator's arrest and relinquishment of possession of the bonds to government authorities the objective of the conspiracy could no longer be attained. But impossibility is not defense to a conspiracy charge, and so again the argument that the entire conspiracy terminated must fail.") (citation omitted).