case DNGN_TRAP_NATURAL:

       case DNGN_TRAP_NATURAL: // only shafts for now
            ostr << "The dungeon contains a number of natural obstacles such "
                    "as shafts, which lead one or two levels down.";
            Options.tutorial_events[TUT_SEEN_TRAP] = 0;
            break;
            

            if (trap_known);

            if (trap_known)

    // disallow shafts on the first two levels
    if (place.branch == BRANCH_MAIN_DUNGEON
        && you.your_level < 2)
    {
        return (false);
    }

        else if (new_grid == DNGN_TRAP_MAGICAL)

        else if (new_grid == DNGN_TRAP_MAGICAL
                 || new_grid == DNGN_TRAP_NATURAL)

            std::string prompt = "Really step onto that "; // preposition?

            std::string prompt = "Really step ";
                        prompt += (trap_type_at_xy(x,y) == TRAP_ALARM ?
                                   "onto" : "into");
                        prompt += " that ";

                                          DESC_PLAIN, false);

                                          DESC_BASENAME, false);

    // Only shafts on the level immediately above a dangeorus branch

    // Only shafts on the level immediately above a dangerous branch

    textcolor( LIGHTGREY );

    {

        revealTrap = monster->do_shaft();

        if (monster->do_shaft())
            revealTrap = true;

    }

        grd[monster->x][monster->y] = trap_category(env.trap[which_trap].type);

        grd[env.trap[which_trap].x][env.trap[which_trap].y] 
                     = trap_category(env.trap[which_trap].type);

    {
        if (mons_is_fleeing(monster) && intel >= I_NORMAL)
            return (true);

    }

// returns true if the trap should be revealed to the player

    bool nearby  = mons_near(this);
    bool vis     = player_monster_visible(this);

            if (nearby)

            if (mons_near(this))

                if (vis)

                if (player_monster_visible(this))

            return (true);

            return (false);

    if (nearby)
    {
        if (vis)
            mprf("%s falls through a shaft!",
                 name(DESC_CAP_THE).c_str());
        else
            mpr("A shaft briefly opens up in the floor!");
    }

    bool reveal = false;
    if (simple_monster_message(this, " falls through a shaft!"))
        reveal = true;;

    return true;

    return (reveal);

                                          shaft_dest.depth);

                                       shaft_dest.depth);

            return ("shaft trap");

            return ("shaft");