Oneway Tunnels

First part:

TUNNEL; Entities/Rooms/Sprites/Tunnel.png; Left, Right, or Both?; upgrade <--- TUNNEL, upgrade TUNNEL --->, upgrade <-- TUNNEL -->; w50, s150, g5;
<--- TUNNEL; Entities/Rooms/Sprites/Tunnel.png; <--- $KEY7$ ; travel_left; uTUNNEL;
TUNNEL --->; Entities/Rooms/Sprites/Tunnel.png; $KEY7$ --->; travel_right; uTUNNEL;

Second part for functions:

upgrade TUNNEL --->; -; -; Entities/Rooms/Sprites/Tunnel.png; Entities/Rooms/Sounds/ConstructShort.ogg; 0; 24; Travel Right; -;
upgrade <--- TUNNEL; -; -; Entities/Rooms/Sprites/Tunnel.png; Entities/Rooms/Sounds/ConstructShort.ogg; 0; 24; Travel Left; -;
travel_left; -; -; Sprites/bubble.png; Entities/Rooms/Sounds/Travel.ogg; 11; 32; Travel Left; -;
travel_right; -; -; Sprites/bubble.png; Entities/Rooms/Sounds/Travel.ogg; 3; 32; Travel Right; -;