Your class inherits from PandaNode, but PandaNode already provides a property called ‘state’ that conflicts with the one in FSM.
To fix this, I suppose we could rename the ‘state’ variable to something else in FSM.py. But in this case you could also wonder whether inheriting from both PandaNode and FSM is the right thing to do, or whether instead you should use composition (ie. storing the node as a member of the class instead).