def generic_set(key, value, tree = data)
      modify(key, value, tree) || uncomment(key, value, tree) ||
        add_new(key, value, tree)
    end
def generic_set(key, value, tree = data)
      modify(key, value, tree) || uncomment(key, value, tree) ||
        add_new(key, value, tree)
    end
powerfull method that sets any value in config. It try to be
 smart to at first modify existing value, then replace commented out code
 and if even that doesn't work, then append it at the end
 @note prefer to use specialized methods of children