class CartesianProduct
  def self.calculate(a,b)
    #result of the Cartesian product
    res=Array.new
    a.each do |aa|
        b.each do |bb|
            #puts "#{aa} #{bb}"
            res.push([aa,bb])
        end
    end
    res
  end
end

c = CartesianProduct.calculate([:a,:b], [4,5])
puts c.inspect
#i want this
#c.each { |elt| puts elt.inspect }
# [:a, 4]
# [:a, 5]
# [:b, 4]
# [:b, 5]