“ Act of Congress'-s 352 (a) (1) of the Immigration and Nationality Act of 1952, 8 U.S.C. § 1484 (a) (1) , which provides that a naturalized American citizen shall lose his nationality by 'having a continuous residence for three years in the territory of a foreign state of which he was formerly a national or in which the place of his birth is situated * * *.' The District Court concluded that petitioner's complaint presented no substantial constitutional issue and denied petitioner's motion to convene a three-judge court, relying on Lapides v. ”