Unless otherwise provided by this Code or by the law defining the offense, a person is not an accomplice in an offense committed by another person if:
(1) He is a victim of that offense;
(2) The offense is so defined that his conduct is inevitably incident to its commission; or
(3) He terminates his complicity prior to the commission of the offense and:
(a) Wholly deprives his complicity of effectiveness in the commission of the offense; or
(b) Gives timely warning to the law enforcement authorities or otherwise makes reasonable effort to prevent the commission of the offense.