Does the longstanding rule for federal perjury cases that a finding of perjury cannot rest on the uncorroborated testimony of one witness apply to the application of the two-level enhancement for obstruction of justice under the United States Sentencing Guidelines § 3C1.1, when the enhancement is based on perjury?

QUESTION PRESENTED FOR REVIEW Does the longstanding rule for federal perjury cases that a finding of perjury cannot rest on the uncorroborated testimony of one witness apply to the application of the two-level enhancement for obstruction of justice under the United States Sentencing Guidelines § 3C1.1, when the enhancement is based on perjury? i