In addition, provide a method named getStatsTotal that calculates the total of these six stats, then returns the amount. If the total is not positive, it should be set to 0. In addition, create classes Paladin and Necromancer that add some extra functionality. Paladin has a function called lay_on_hands() and when called, it simply prints out "You are healed". Necromancer has a function called summon_zombie() and when called, it prints: "Zombies are coming". Other than these, they are simply extending Character class (they are children of the Character class). Implement this hierarchy.