This court declared that, before a person can avail himself of the plea of self-defense against the charge of homicide, he must do everything in his power, consistent with his safety, to avoid the danger and avoid the necessity of taking life. If one has reason to believe that he will be attacked, in a manner which threatens him with bodily injury, he must avoid the attack if it is possible to do so, and the right of self-defense does not arise until he has done everything in his power to prevent its necessity.