The methods Partition.add_*_border_strip where * is horizontal or vertical return new partitions. This ticket proposes a method that returns the indices of the cells of these new partitions which are not in the original partition.

Depends on #34339

CC: @tscrim @trevorkarn

Component: combinatorics

Keywords: gsoc2022 partition cell border-strip

Author: Trevor K. Karn

Branch/Commit: 218b548

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/34345