slice function params

[jaroslavlibal]

The docs for the slice function says:

Returns a lazy collection of items which are part of the original collection from item number $from to item number $to inclusive. The items before $from are also realized, just not returned.

But its $to param usage is exclusive in the implementation:
if ($index >= $from && ($index < $to || $to == -1))

Also, naming an index (starting at zero) as the item number may be a little confusing.

Did I get something wrong, please? If this is an issue, is it a documentation or implementation one? Is it intended to be inclusive or exclusive?