if xx: 与if xx is not None:
主要是为了记录python中的if xx: 与if xx is not None:细节问题。if xx is not None: = if xx != Noneif xx: = if xx != None and xx != " " and xx != False and xx != 0 and xx != [] and xx != {} and....xx is not None 只是判断xx是不是 None 类型,如果不是None 类型,则返回True。假设xx==0,