Add Border

Erlang Add Border

-module(add_border).
-export([add_border/1]).

add_border(Picture) ->
    Width = length(hd(Picture)),
    Border = lists:duplicate(Width + 2, $*),
    Bordered = [[$*] ++ Row ++ [$*] || Row <- Picture],
    [Border] ++ Bordered ++ [Border].

This builds a new grid with a * border around every side. It adds a full top and bottom row, then wraps each existing row from left and right.