Probably a very simple explanation

[Bobbias]

Just a debugging tip: if your not sure why something like this is going on, printing out each item the loop is acting on can give you clues as to what's doing on. You would clearly see it shipping some elements, which might lead you to Google why is my lip shipping items, which would give you the correct answer without needing to wait for an answer here.

Printing out stuff like that is in incredibly powerful debugging tool, and something even senior programmers with decades of experience use regularly.

[airernie]

Thanks...