Any stop or turn signal required by section 14-242 or 14-243 may be given either by means of the hand and arm or by a signal lamp or lamps or mechanical signal device. Hand signals shall be as follows: (1) To stop or decrease speed: Hand and arm extended downward; (2) to turn left or to leave or draw away from a curb or the edge of the highway: Hand and arm extended horizontally with forefinger pointed; (3) to turn right: Hand and arm extended upward. Each operator of a motor vehicle who makes a turn signal by means of signal lamps or mechanical signal device shall turn in the direction indicated and return such signal to the nonoperating position immediately after completing the movement for which a signal has been given. Violation of any of the provisions of this section shall be an infraction.