Display the current state of the environment. Display a 'picture' of the current state of the environment. Run n environments with an identical agent in each, and average the scores. You won't be creating instances of grid-environment directly, but it is the key structure that is inherited by the Vacuum, Wumpus, Shopping and Elevator worlds. An object is anything that occupies space.
Some objects are 'alive'.
Execute the actions and do bookkeeping on the bump sensor. Build a new environment with all the agents and objects in place. This gets passed an environment which may need to have the objects placed. By default, we stop when there are no live agents. Show what is in each location in the environment.