step function effect in fourrooms doesn't fit the description

[Mingpan]

In the description it reads:
The agent can perform one of four actions,
up, down, left or right, which have a stochastic effect. With probability 2/3, the actions
cause the agent to move one cell in the corresponding direction, and with probability 1/3,
the agent moves instead in one of the other three directions, each with 1/9 probability. In
either case, if the movement would take the agent into a wall then the agent remains in the
same cell.

However, if I understand the code correctly, the self.currentcell is set to be the next cell before the random process happens. Therefore the agent will land in next cell with prob 2/3, which is correct, but with prob 1/3 it will land in the neighboring cells of the nextcell (equivalent to taking an additional step). That doesn't seem to fit the description above and in the paper.

[tsaket]

+1