Suppose I have a class `A`

```
class A
  attr_accessor :x, :y

  def initialize(x,y)
    @x, @y = x, y
  end
end

```

How can I get `x` and `y` attributes without knowing how exactly they were named. 

E.g.

```
a = A.new(5,10)
a.attributes # => [5, 10]

```