Junction and corner characters (tees, crosses).
@type t() :: %Boxart.Charset.Junctions{ corner_bottom_left: String.t(), corner_bottom_right: String.t(), corner_top_left: String.t(), corner_top_right: String.t(), cross: String.t(), tee_down: String.t(), tee_left: String.t(), tee_right: String.t(), tee_up: String.t() }