Appellant was indicted, tried by a jury and found guilty of traveling in interstate commerce for the purpose of promoting prostitution in violation of 18 U.S.C. § 1952.

Appellant’s sole contention is that the trial judge committed reversible error in calling a witness, at the suggestion of the government, and then refreshing the recollection of, or, impeaching the witness with her prior statements. Beyond question, the statements were helpful to the government’s case. On the record before us, the question of whether the judge abused his discretion is a close one. However, we need not answer the question. The evidence of the guilt of the appellant is otherwise so overwhelming that the error, if any, is harmless and did not affect his substantial rights. See, Rule 52 F.R.Crim.P.

Judgment affirmed.