Fix EightPuzzle class implementation in search.py (#710) (#733)
Fix EightPuzzle class implementation in search.py (#710) (#733)

* Fix EightPuzzle class implementation

* Fix EightPuzzle class implementation (#710)

* Address style issues (#710)

aimacode/aima-python,jo-tez/aima-python,Chipe1/aima-python,aimacode/aima-python,Chipe1/aima-python,jo-tez/aima-python