In Adams v. United States, 95 U.S.App.D.C. 354, 222 F.2d 45, 47 (1955), appellant contended that his trial counsel was incompetent in that he had failed to subpoena a material witness. In holding that a hearing under section 2255 of Title 28 U.S.C. was not required, the court said: "As to the absent witness, appellant does not say what the substance of his testimony would have been, asserting merely that it would have established his innocence. Thus, on the face of the record, appellant's present allegations - even if true - would not sustain his claim that he was not given a fair trial and that his sentence should be set aside".