tuple是位于builtins模块中的内置类，无需import模块就可直接使用，其实所有的元组都是该tuple内置类对象实例。
tuple类构造函数
语法
def __init__(self, seq=()):
参数
- tuple()，不传任何参数，表示创建一个空元组对象；
- tuple(iterable)，传一个可遍历的数据对象，创建一个每个遍历项作为数据项的元组对象；如果传的是一个元组对象，返回的复制该元组的对象；
tuple类的方法
tuple类count方法
def count(self, value):
tuple的count方法表示查找元素value在tuple对象中出现次数。
tuple类index方法
def index(self, value, start=None, stop=None):
tuple的index方法表示查找元素value在tuple中第一个索引值；此外可以通过start和stop参数指定搜索的起始索引点和结束索引点。
tuple类逻辑运算等特殊方法
def __add__(self, *args, **kwargs):
""" Return self+value. """
pass
def __contains__(self, *args, **kwargs):
""" Return key in self. """
pass
def __eq__(self, *args, **kwargs):
""" Return self==value. """
pass
def __getattribute__(self, *args, **kwargs):
""" Return getattr(self, name). """
pass
def __getitem__(self, *args, **kwargs):
""" Return self[key]. """
pass
def __getnewargs__(self, *args, **kwargs):
pass
def __ge__(self, *args, **kwargs):
""" Return self>=value. """
pass
def __gt__(self, *args, **kwargs):
""" Return self>value. """
pass
def __hash__(self, *args, **kwargs):
""" Return hash(self). """
pass
def __iter__(self, *args, **kwargs):
""" Implement iter(self). """
pass
def __len__(self, *args, **kwargs):
""" Return len(self). """
pass
def __le__(self, *args, **kwargs):
""" Return self<=value. """
pass
def __lt__(self, *args, **kwargs):
""" Return self<value. """
pass
def __mul__(self, *args, **kwargs):
""" Return self*value.n """
pass
def __ne__(self, *args, **kwargs):
""" Return self!=value. """
pass
def __repr__(self, *args, **kwargs):
""" Return repr(self). """
pass
def __rmul__(self, *args, **kwargs):
""" Return self*value. """
pass