find-last-by-pos

Return `zloc` located at the last node spanning position `pos` that satisfies the predicate `p?`, else `nil`. - `zloc` location is (inclusive) starting point for `pos` depth-first search - `pos` can be a `{:row :col}` map or a `[row col]` vector. The `row` and `col` values are 1-based and relative to the start of the form represented by the zipper. - `p?` is optional and defaults to `(constantly true)` Throws if `zloc` was not created with [position tracking](/doc/01-user-guide.adoc#position-tracking). NOTE: Whitespace and comment nodes are included in the search.