"No person shall be registered as an elector of this State or be allowed to vote in any election herein, unless he be able to read and write any section of the constitution of the State of Oklahoma; but no person who was, on January 1, 1866, or at any time prior thereto, entitled to vote under any form of government, or who at that time resided in some foreign nation, and no lineal descendant of such person, shall be denied the right to register and vote because of his inability to so read and write sections of such constitution." What requirement needed to be met in order to vote in Oklahoma, according to this 1910 state law?