if something door something else then that something has a uncertain wall on that something else
directions_to_get_somewhere is how_to_thing. boundary_line is unnatural_thing. interior_door is tangible_thing. another_way_to_say_separates_things is divides_objects. peace_wall is tangible_thing. wall is geographical_thing. lost_river is tangible_thing. stuck is being_somewhere. being_somewhere is situation. sea_wall is tangible_thing.