例如： class str(object): """ str(object='') -> str str(bytes_or_buffer[, encoding[, errors]]) -> str Create a new string object from the given object. If encoding or errors is specified, then the object must expose a data buffer that will be decoded using the given encoding and error handler. Otherwise, returns the result of object.__str__() (if defined) or repr(object). encoding defaults to sys.getdefaultencoding(). errors defaults to 'strict'. """ 其中一個(gè)函數(shù) def capitalize(self): # real signature unknown; restored from __doc__ """ S.capitalize() -> str Return a capitalized version of S, i.e. make the first character have upper case and the rest lower case. """ return "" 這個(gè)函數(shù)到底返回了什么？難道返回了一個(gè)空字符嗎？ def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__ """ S.endswith(suffix[, start[, end]]) -> bool Return True if S ends with the specified suffix, False otherwise. With optional start, test S beginning at that position. With optional end, stop comparing S at that position. suffix can also be a tuple of strings to try. """ return False 這個(gè)函數(shù)，返回False ，什么意思？ def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ """ S.find(sub[, start[, end]]) -> int Return the lowest index in S where substring sub is found, such that sub is contained within S[start:end]. Optional arguments start and end are interpreted as in slice notation. Return -1 on failure. """ return 0 這個(gè)返回一個(gè)0 ？ def format(self, *args, **kwargs): # known special case of str.format """ S.format(*args, **kwargs) -> str Return a formatted version of S, using substitutions from args and kwargs. The substitutions are identified by braces ('{' and '}'). """ pass 這個(gè)是一pass結(jié)尾的，那么要這個(gè)函數(shù)有什么意義 但是我在實(shí)際應(yīng)用他們的時(shí)候，返回的并不是這樣的？ 我現(xiàn)在的以為是：這個(gè)類里面的這些函數(shù)，函數(shù)體里面什么邏輯都沒(méi)有寫？那么函數(shù)是怎么運(yùn)行的？