@Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        SquaredWorld other = (SquaredWorld) obj;
        if (obstacles == null) {
            if (other.obstacles != null)
                return false;
        } else if (!obstacles.equals(other.obstacles))
            return false;
        if (side != other.side)
            return false;
        return true;
    }