dir(builtins)
输出：
['ArithmeticError','AssertionError','AttributeError','BaseException','BufferError','BytesWarning','DeprecationWarning','EOFError','Ellipsis','EnvironmentError','Exception','False','FloatingPointError','FutureWarning','GeneratorExit','IOError','ImportError','ImportWarning','IndentationError','IndexError','KeyError','KeyboardInterrupt','LookupError','MemoryError','NameError','None','NotImplemented','NotImplementedError','OSError','OverflowError','PendingDeprecationWarning','ReferenceError','RuntimeError','RuntimeWarning','StandardError','StopIteration','SyntaxError','SyntaxWarning','SystemError','SystemExit','TabError','True','TypeError','UnboundLocalError','UnicodeDecodeError','UnicodeEncodeError','UnicodeError','UnicodeTranslateError','UnicodeWarning','UserWarning','ValueError','Warning','ZeroDivisionError','debug','doc',
'import','name','package','abs','all','any','apply','basestring','bin','bool','buffer','bytearray','bytes','callable','chr','classmethod','cmp','coerce','compile','complex','copyright','credits','delattr','dict','dir','divmod','enumerate','eval','execfile','exit','file','filter','float','format','frozenset','getattr','globals','hasattr','hash','help','hex','id','input','int','intern','isinstance','issubclass','iter','len','license','list','locals','long','map','max','memoryview','min','next','object','oct','open','ord',
'pow','print','property','quit','range','raw_input','reduce','reload','repr','reversed','round','set','setattr','slice','sorted','staticmethod','str','sum','super','tuple','type','unichr','unicode','vars','xrange','zip'
]

help(max)
输出：Help on built-in function max in module builtin:max(…)max(iterable[, key=func]) -> valuemax(a, b, c, …[, key=func]) -> value在单个可迭代参数中，返回其最大的项。使用两个或多个参数，返回最大的参数。 

      import mathmath.sqrt(16) # 输出4.0         

import math
print(dir(math))
输出：    ['doc', 'name', 'package', 'acos', 'acosh','asin', 'asinh', 'atan', 'atan2', 'atanh', 'ceil', 'copysign','cos', 'cosh', 'degrees', 'e', 'erf', 'erfc', 'exp', 'expm1','fabs', 'factorial', 'floor', 'fmod', 'frexp', 'fsum', 'gamma','hypot', 'isinf', 'isnan', 'ldexp', 'lgamma', 'log', 'log10','log1p', 'modf', 'pi', 'pow', 'radians', 'sin', 'sinh', 'sqrt','tan', 'tanh', 'trunc']

""" 这是模块内函数的定义."""def sayHello():"""这是模块内函数的代码"""return 'Hello World'

       import helloWorldhelloWorld.__doc__'这是模块的描述'helloWorld.sayHello.__doc__'这是函数的描述'         

class MyClassObject(object):pass

dir(MyClassObject)
输出：['class', 'delattr', 'dict', 'doc', 'format', 'getattribute', 'hash','init', 'module', 'new', 'reduce', 'reduce_ex', 'repr', 'setattr','sizeof', 'str', 'subclasshook', 'weakref']

str(123)#输出 "123"，因为默认的print打印都会转成Str字符串打印到屏幕