OPINION — AG — QUESTION: "A REAL ESTATE MORTGAGE EXECUTED TO THE SMALL BUSINESS ADMINISTRATION, SAME BEING AN INSTRUMENTALITY OF THE UNITED STATES, IS SUBJECT TO THE MORTGAGE REGISTRATION TAX PROVIDED FOR IN 68 O.S. 1961, 1171-1182 [68-1171] — [68-1182], AS A CONDITION PRECEDENT TO RECORDING OF SUCH MORTGAGE BY THE COUNTY CLERK?" — NEGATIVE CITE: ARTICLE X, SECTION 6, OPINION NO. MARCH 22, 1939 — MELTON (FRED HANSEN)