用来大写变小写，小写变大写
def fun(x): lst=[lbk][rbk] for i in range(len(x)): if x[lbk]i[rbk].islower: lst.append((x[lbk]i[rbk]).upper()) elif x[lbk]i[rbk].isupper: lst.append((x[lbk]i[rbk]).lower()) return ''.join(lst)s=input('请输入字母：')x=list(s)h=str(fun(x))print(h)
