It started as a discussion with a friend, who didn't fully grasp some way of setting defaults, but I thought the idea was cool enough for a beginner kata: binary OR each matching element of two given arrays (or lists, if you do it in Python; vectors in c++) of integers and give the resulting ORed array [starts to sound like a tonguetwister, doesn't it?].
If one array is shorter than the other, use the optional third parameter (defaulted to 0) to OR the unmatched elements.
For example:
orArrays([1,2,3],[1,2,3]) == [1,2,3]
orArrays([1,2,3],[4,5,6]) == [5,7,7]
orArrays([1,2,3],[1,2]) == [1,2,3]
orArrays([1,2],[1,2,3]) == [1,2,3]
orArrays([1,2,3],[1,2,3],3) == [1,2,3]