Checking Multiple Images and Choose Next One

Basically I want something like this, its written on Sikuli.

Iterator<Match> it = s.findAll(Imagepath);



while(it.hasNext()){

   System.out.println("the match is "+it.next().click());

}
Do we have hasNext() function in ankulua?

Here is what I try to write in lua

a = Pattern("image.png"):similar(0.7)
b = Pattern("image2.png"):similar(0.7)
r = Region(1922, 5, 400, 910)

all = r:findAll(a)

-- I know its not gonna work need advice to write this code in lua

while(all.hasNext()) do --I want to iterate as many as "a" images on "r"
 click(all[0]) --I want the script to click the first "a"
 if(notExist(b)) then
   click(all.next) --This mean, If "b" not exist, i want to click next "a".
 end
end



So.. what I try to achieve here is.
1. I Want to iterate as many as image1 in a region.
2. If dont see image2, I want to check on next image1.

I'm bit new in programming. So I might be screw my logic here.
Thank you.