split
Modifies @orig to cover only the text after @split_index, and returns a new item that covers the text before @split_index that used to be in @orig.
You can think of @split_index as the length of the returned item.
Return
the newly allocated item representing text before
Since
1.2
Parameters
text
text to which positions in @orig apply
splitIndex
byte index of position to split item, relative to the start of the item