Python - I'm getting a error saying 'can't assign to literal' : I'm trying to get this procedure check whether the user lands on a treasure square and if they do they get gold. Also the treasure can only be landed on 3 times until it turns into a bandit, therefore after each time the player lands on it the tiles name changes, to T2, T3, B. Whenever i attempt to run my code a error appear saying 'can't assign to literal'

This is my code:

[1]: https://i.stack.imgur.com/uxg51.png

If anybody could help out i'd be grateful.