class AbstractWorld:
    height = 0
    width = 0
    board = []
    def __init__(self, height, width):
        self.height = height
        self.width = width
    def set_creature(self, x, y, creature):
        pass #abstract
    def get_creature(self, x, y):
        pass #abstract
    def addListener(WorldListener):
        pass
    def step():
        pass

class LocalWorld(AbstractWorld):     
    def set_board_zeroes(self):
        x = 0
        y = 0
        while y < self.height:
            x = 0
            y+= 1
            while x < self.width:
                self.board.append(0)
                x+=1
    def print_board(self):
        print(len(self.board))
        y = 0
        while y < self.height:
            x = 0
            y+=1
            while x < self.width:
                print (self.board[x*y])
                x+=1
                
    def set_creature(self, x, y, creature):
        self.board[x*y] = creature
        
    def get_creature(self, x, y):
        return self.board[x*y]