我导入了pandas.tseries.holiday库。
from pandas.tseries.holiday import *
调用函数USFederalHolidayCalendar
cal = USFederalHolidayCalendar()
然后我试图调用CustomBusinessDay，它给了我错误：
cbd = CustomBusinessDay(holidays=cal.holidays())
NameError: name 'CustomBusinessDay' is not defined
我错过了什么吗？