org-list-get-prev-item
org-list-get-prev-item is a compiled Lisp function in `org-list.el
'.
(org-list-get-prev-item ITEM STRUCT PREVS)
Return previous item in same sub-list as ITEM, or nil.
STRUCT is the list structure. PREVS is the alist of previous
items, as returned by `org-list-prevs-alist'.