offsets a pattern list generated below to a random
        position in the grid

def random_offset(self, lst):
        """ 
        offsets a pattern list generated below to a random
        position in the grid
        """
        res = []
        x = random.randint(4,self.max_x - 42)
        y = random.randint(4,self.max_y - 10)
        for itm in lst:
            res.append([itm[0] + y, itm[1] + x])
        return res