allout-shift-in is an interactive compiled Lisp function in `allout.el'.

(allout-shift-in ARG)

Increase depth of current heading and any items collapsed within it.

With a negative argument, the item is shifted out using
`allout-shift-out', instead.

With an argument greater than one, shift-in the item but not its
offspring, making the item into a sibling of its former children,
and a child of sibling that formerly preceded it.

You are not allowed to shift the first offspring of a topic
inwards, because that would yield a "containment
discontinuity", where the depth difference between a topic and
its immediate offspring is greater than one. The first topic in
the file can be adjusted to any positive depth, however.