请问一下各位大佬，这个哪里出错了？为什么错了？要怎么改呢？
months = set('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sept','Oct','Nov','Dec')
x1 = 'Feb'
x2 = 'Mar'
if x1 in months:
print 'x1: ok'
else:
print 'x1: error'
if x2 in months:
print 'x2: ok'
else:
print 'x2: error'
