摘要：
英文文档： sum(iterable[, start]) Sums start and the items of an iterable from left to right and returns the total. start defaults to 0. The iterable‘s ite 阅读全文
摘要：
英文文档： class str(object='') class str(object=b'', encoding='utf-8', errors='strict') Return a string version of object. If object is not provided, retu 阅读全文