新手小问题

>>> bestVehicleFor(10,10,10,10,10,10,10,10,10)
'veh1NameCost' is 90.0
10
>>> bestVehicleFor(10,a,10,10,10,10,10,10,10)
Traceback (most recent call last):
File "<pyshell#10>", line 1, in <module>
bestVehicleFor(10,a,10,10,10,10,10,10,10)
NameError: name 'a' is not defined
>>>