Upadte search.py (#389)
Upadte search.py (#389)

minor error fixes.
sofmonk/aima-python,SnShine/aima-python,jo-tez/aima-python,jo-tez/aima-python,Chipe1/aima-python,aimacode/aima-python,Chipe1/aima-python,aimacode/aima-python,SnShine/aima-python,sofmonk/aima-python