How should I write a function for (flood filled image function iterator) ?

I would like to write a new function for the floodfilledimagefunctioniterator but I don’t know how should I write one.

I am following what has been suggested here: Floodfill segmentation or is there an other possibillity in itk (narkive.com).

Is there any example that I could follow?

Thank you in advance,

Rafael