Foo Class

class Foo
    attr_reader :x, :y
    
    def initialize(x,y)
      @x = x
      @y = y
    end

  def ==(other)
    if !self.instance_of?(other.class)
      false
    elsif self.equal?(other)
      true
    else
      @x == other.x && @y == other.y
    end
  end

  def eql?(other)
    self == other
  end

#Hash method is generally not required to override.
  def hash
    [@x,@y].hash *31
  end

end