python进阶-常用内建库

from datetime import datetime


now = datetime.now()  # 获取当前时间
print(now)  # 2021-08-17 09:10:59.819930
print(type(now))  # <class 'datetime.datetime'>

from datetime import datetime


dt = datetime(2015, 4, 19, 12, 20)  # 用指定日期时间创建datetime
print(dt)  # 2015-04-19 12:20:00

from datetime import datetime


dt = datetime(2015, 4, 19, 12, 20)  # 用指定日期时间创建datetime
dt.timestamp()  # 把datetime转换为timestamp
# 1429417200.0

from datetime import datetime


t = 1429417200.0
print(datetime.fromtimestamp(t))  # 2015-04-19 12:20:00

from datetime import datetime


t = 1429417200.0
print(datetime.fromtimestamp(t)) # 本地时间
# 2015-04-19 12:20:00
print(datetime.utcfromtimestamp(t)) # UTC时间
# 2015-04-19 04:20:00

from datetime import datetime


cday = datetime.strptime('2015-6-1 18:19:59', '%Y-%m-%d %H:%M:%S')
print(cday)  # 2015-06-01 18:19:59

from datetime import datetime


now = datetime.now()
print(now.strftime('%a, %b %d %H:%M'))  # Tue, Aug 17 09:10

>>> from datetime import datetime, timedelta
>>> now = datetime.now()
>>> now
datetime.datetime(2021, 8, 17, 10, 11, 27, 797823)
>>> now + timedelta(hours = 10)
datetime.datetime(2021, 8, 17, 20, 11, 27, 797823)
>>> now - timedelta(days = 1)
datetime.datetime(2021, 8, 16, 10, 11, 27, 797823)
>>> now + timedelta(days = 2, hours = 12)
datetime.datetime(2021, 8, 19, 22, 11, 27, 797823)

>>> from datetime import datetime, timedelta, timezone
>>> tz_utc_8 = timezone(timedelta(hours=8)) # 创建时区UTC+8:00
>>> now = datetime.now()
>>> now
datetime.datetime(2015, 5, 18, 17, 2, 10, 871012)
>>> dt = now.replace(tzinfo=tz_utc_8) # 强制设置为UTC+8:00
>>> dt
datetime.datetime(2015, 5, 18, 17, 2, 10, 871012, tzinfo=datetime.timezone(datetime.timedelta(0, 28800)))

# 拿到UTC时间，并强制设置时区为UTC+0:00:
>>> utc_dt = datetime.utcnow().replace(tzinfo=timezone.utc)
>>> print(utc_dt)
2021-08-17 02:34:19.972780+00:00
# astimezone()将转换时区为北京时间:
>>> bj_dt = utc_dt.astimezone(timezone(timedelta(hours=8)))
>>> print(bj_dt)
2021-08-17 10:34:19.972780+08:00
# astimezone()将转换时区为东京时间:
>>> tokyo_dt = utc_dt.astimezone(timezone(timedelta(hours=9)))
>>> print(tokyo_dt)
2021-08-17 11:34:19.972780+09:00
# astimezone()将bj_dt转换时区为东京时间:
>>> tokyo_dt2 = bj_dt.astimezone(timezone(timedelta(hours=9)))
>>> print(tokyo_dt2)
2021-08-17 11:34:19.972780+09:00

# Hello.py
# -*- coding:utf-8 -*-

import re
from datetime import datetime, timezone, timedelta

def to_timestamp(dt_str, tz_str):
    timeNow = datetime.strptime(dt_str, '%Y-%m-%d %H:%M:%S')
    tz = re.match(r'UTC(\+|\-)0?(\d{1,2}):00', tz_str)
    tz = int((str(tz[1])+str(tz[2])))
    dt = timeNow.replace(tzinfo=timezone(timedelta(hours=tz)))
    return dt.timestamp()


# 测试:
t1 = to_timestamp('2015-6-1 08:10:30', 'UTC+7:00')
assert t1 == 1433121030.0, t1

t2 = to_timestamp('2015-5-31 16:10:30', 'UTC-09:00')
assert t2 == 1433121030.0, t2

print('ok')

>>> from collections import namedtuple
>>> Point = namedtuple('Point', ['x', 'y'])
>>> p = Point(1, 2)
>>> p.x
1
>>> p.y
2

>>> isinstance(p, Point)
True
>>> isinstance(p, tuple)
True

>>> from collections import deque
>>> q = deque(['a', 'b', 'c'])
>>> q.append('x')
>>> q.appendleft('y')
>>> q
deque(['y', 'a', 'b', 'c', 'x'])

>>> from collections import defaultdict
>>> dd = defaultdict(lambda: 'N/A')
>>> dd['key1'] = 'abc'
>>> dd['key1'] # key1存在
'abc'
>>> dd['key2'] # key2不存在，返回默认值
'N/A'

>>> from collections import OrderedDict
>>> d = dict([('a', 1), ('b', 2), ('c', 3)])
>>> d # dict的Key是无序的
{'a': 1, 'c': 3, 'b': 2}
>>> od = OrderedDict([('a', 1), ('b', 2), ('c', 3)])
>>> od # OrderedDict的Key是有序的
OrderedDict([('a', 1), ('b', 2), ('c', 3)])

>>> od = OrderedDict()
>>> od['z'] = 1
>>> od['y'] = 2
>>> od['x'] = 3
>>> list(od.keys()) # 按照插入的Key的顺序返回
['z', 'y', 'x']

from collections import OrderedDict

class LastUpdatedOrderedDict(OrderedDict):

    def __init__(self, capacity):
        super(LastUpdatedOrderedDict, self).__init__()
        self._capacity = capacity

    def __setitem__(self, key, value):
        containsKey = 1 if key in self else 0
        if len(self) - containsKey >= self._capacity:
            last = self.popitem(last=False)
            print('remove:', last)
        if containsKey:
            del self[key]
            print('set:', (key, value))
        else:
            print('add:', (key, value))
        OrderedDict.__setitem__(self, key, value)

from collections import ChainMap
import os, argparse

# 构造缺省参数:
defaults = {
    'color': 'red',
    'user': 'guest'
}

# 构造命令行参数:
parser = argparse.ArgumentParser()
parser.add_argument('-u', '--user')
parser.add_argument('-c', '--color')
namespace = parser.parse_args()
command_line_args = { k: v for k, v in vars(namespace).items() if v }

# 组合成ChainMap:
combined = ChainMap(command_line_args, os.environ, defaults)

# 打印参数:
print('color=%s' % combined['color'])
print('user=%s' % combined['user'])

$ python3 use_chainmap.py 
color=red
user=guest

$ python3 use_chainmap.py -u bob
color=red
user=bob

$ user=admin color=green python3 use_chainmap.py -u bob
color=green
user=bob

>>> from collections import Counter
>>> c = Counter()
>>> for ch in 'programming':
...     c[ch] = c[ch] + 1
...
>>> c
Counter({'g': 2, 'm': 2, 'r': 2, 'a': 1, 'i': 1, 'o': 1, 'n': 1, 'p': 1})
>>> c.update('hello') # 也可以一次性update
>>> c
Counter({'r': 2, 'o': 2, 'g': 2, 'm': 2, 'l': 2, 'p': 1, 'a': 1, 'i': 1, 'n': 1, 'h': 1, 'e': 1})

['A', 'B', 'C', ... 'a', 'b', 'c', ... '0', '1', ... '+', '/']

>>> import base64
>>> base64.b64encode(b'binary\x00string')
b'YmluYXJ5AHN0cmluZw=='
>>> base64.b64decode(b'YmluYXJ5AHN0cmluZw==')
b'binary\x00string'

>>> base64.b64encode(b'i\xb7\x1d\xfb\xef\xff')
b'abcd++//'
>>> base64.urlsafe_b64encode(b'i\xb7\x1d\xfb\xef\xff')
b'abcd--__'
>>> base64.urlsafe_b64decode('abcd--__')
b'i\xb7\x1d\xfb\xef\xff'

# 标准Base64:
'abcd' -> 'YWJjZA=='
# 自动去掉=:
'abcd' -> 'YWJjZA'

# -*- coding: utf-8 -*-
import base64


def safe_base64_decode(s):  # 拿到去掉=后的base64字符串后，为其自动补充=
    l = len(s)
    n = 4 - l%4
    if not n == 4:
        while n:
            s += '='
            n -= 1
    print(s)
    return base64.b64decode(s)


# 测试:
assert b'abcd' == safe_base64_decode('YWJjZA=='), safe_base64_decode('YWJjZA==')
assert b'abcd' == safe_base64_decode('YWJjZA'), safe_base64_decode('YWJjZA')
print('ok')

>>> n = 10240099
>>> b1 = (n & 0xff000000) >> 24
>>> b2 = (n & 0xff0000) >> 16
>>> b3 = (n & 0xff00) >> 8
>>> b4 = n & 0xff
>>> bs = bytes([b1, b2, b3, b4])
>>> bs
b'\x00\x9c@c'

>>> import struct
>>> struct.pack('>I', 10240099)
b'\x00\x9c@c'

>>> struct.unpack('>IH', b'\xf0\xf0\xf0\xf0\x80\x80')
(4042322160, 32896)

>>> s = b'\x42\x4d\x38\x8c\x0a\x00\x00\x00\x00\x00\x36\x00\x00\x00\x28\x00\x00\x00\x80\x02\x00\x00\x68\x01\x00\x00\x01\x00\x18\x00'

>>> struct.unpack('<ccIIIIIIHH', s)
(b'B', b'M', 691256, 0, 54, 40, 640, 360, 1, 24)

# -*- coding: utf-8 -*-
import base64, struct


bmp_data = base64.b64decode('Qk1oAgAAAAAAADYAAAAoAAAAHAAAAAoAAAABABAAAAAAADICAAASCwAAEgsAA' +
'AAAAAAAAAAA/3//f/9//3//f/9//3//f/9//3//f/9//3//f/9//3//f/9//3//f/9//3/' +
'/f/9//3//f/9//3//f/9/AHwAfAB8AHwAfAB8AHwAfP9//3//fwB8AHwAfAB8/3//f/9/A' + 'HwAfAB8AHz/f/9//3//f/9//38AfAB8AHwAfAB8AHwAfAB8AHz/f/9//38AfAB8/3//f/9' +
'//3//fwB8AHz/f/9//3//f/9//3//f/9/AHwAfP9//3//f/9/AHwAfP9//3//fwB8AHz/f' +
'/9//3//f/9/AHwAfP9//3//f/9//3//f/9//38AfAB8AHwAfAB8AHwAfP9//3//f/9/AHw' +
'AfP9//3//f/9//38AfAB8/3//f/9//3//f/9//3//fwB8AHwAfAB8AHwAfAB8/3//f/9//' +
'38AfAB8/3//f/9//3//fwB8AHz/f/9//3//f/9//3//f/9/AHwAfP9//3//f/9/AHwAfP9' +
'//3//fwB8AHz/f/9/AHz/f/9/AHwAfP9//38AfP9//3//f/9/AHwAfAB8AHwAfAB8AHwAf' +
'AB8/3//f/9/AHwAfP9//38AfAB8AHwAfAB8AHwAfAB8/3//f/9//38AfAB8AHwAfAB8AHw' +
'AfAB8/3//f/9/AHwAfAB8AHz/fwB8AHwAfAB8AHwAfAB8AHz/f/9//3//f/9//3//f/9//' +
'3//f/9//3//f/9//3//f/9//3//f/9//3//f/9//3//f/9//3//f/9//38AAA==')



def bmp_info(data):
    data = data[0:30]
    byteStr = struct.unpack('<ccIIIIIIHH', data)
    if byteStr[0] == b'B' and byteStr[1] == b'M' or b'A':
        return {
            'width': byteStr[-4],
            'height': byteStr[-3],
            'color': byteStr[-1]
        }


# 测试
bi = bmp_info(bmp_data)
assert bi['width'] == 28
assert bi['height'] == 10
assert bi['color'] == 16
print('ok')

import hashlib


md5 = hashlib.md5()
md5.update('how to use md5 in puthon hashlib'.encode('utf-8'))
print(md5)

bd3c2bf3a86acaa6ee89efda6b5ceae4

import hashlib

md5 = hashlib.md5()
md5.update('how to use md5 in '.encode('utf-8'))
md5.update('python hashlib?'.encode('utf-8'))
print(md5.hexdigest())

import hashlib

sha1 = hashlib.sha1()
sha1.update('how to use sha1 in '.encode('utf-8'))
sha1.update('python hashlib?'.encode('utf-8'))
print(sha1.hexdigest())

2c76b57293ce30acef38d98f6046927161b46a44

def calc_md5(password):
    return get_md5(password + 'the-Salt')

# -*- coding: utf-8 -*-
import hashlib, random


# 用户类
class User(object):
    def __init__(self, username, password):
        self.username = username
        self.salt = ''.join([chr(random.randint(48, 122)) for i in range(20)])
        self.password = get_md5(password + self.salt)

# 模拟用户信息数据库
db = {
    'michael': User('michael', '123456'),
    'bob': User('bob', 'abc999'),
    'alice': User('alice', 'alice2008')
}
# 根据用户输入的登录名和口令模拟用户注册，计算更安全的MD5
def register(username, password):
    newUser = User(username, password)
    db[username] = User.password
	return newUser


# 然后，根据修改后的MD5算法实现用户登录的验证
def get_md5(s):
    return hashlib.md5(s.encode('utf-8')).hexdigest()


# 登陆验证
def login(username, password):
    user = db[username]
    return user.password == get_md5(password + user.salt)


# 测试:
assert login('michael', '123456')
assert login('bob', 'abc999')
assert login('alice', 'alice2008')
assert not login('michael', '1234567')
assert not login('bob', '123456')
assert not login('alice', 'Alice2008')
print('ok')

import hmac


message = b'Hello, world!'
key = b'secret'
h = hmac.new(key, message, digestmod = 'MD5')
print(h.hexdigest())

fa4ee7d173f2d97ee79022d1a7355bcf

# -*- coding: utf-8 -*-
import hmac, random


# 用户类
class User(object):
    def __init__(self, username, password):
        self.username = username
        self.salt = ''.join([chr(random.randint(48, 122)) for i in range(20)])
        self.password = hmac_md5(self.salt, password)

# 模拟用户信息数据库
db = {
    'michael': User('michael', '123456'),
    'bob': User('bob', 'abc999'),
    'alice': User('alice', 'alice2008')
}
# 根据用户输入的登录名和口令模拟用户注册，计算更安全的MD5
def register(username, password):
    newUser = User(username, password)
    db[username] = User.password
	return newUser


# 然后，根据修改后的MD5算法实现用户登录的验证
def hmac_md5(key, s):
    return hmac.new(key.encode('utf-8'), s.encode('utf-8'), 'MD5').hexdigest()


# 登陆验证
def login(username, password):
    user = db[username]
    return user.password == get_md5(user.salt, password)


# 测试:
assert login('michael', '123456')
assert login('bob', 'abc999')
assert login('alice', 'alice2008')
assert not login('michael', '1234567')
assert not login('bob', '123456')
assert not login('alice', 'Alice2008')
print('ok')

>>> import itertools
>>> natuals = itertools.count(1)
>>> for n in natuals:
...     print(n)
...
1
2
3
...

>>> import itertools
>>> cs = itertools.cycle('ABC') # 注意字符串也是序列的一种
>>> for c in cs:
...     print(c)
...
'A'
'B'
'C'
'A'
'B'
'C'
...

>>> ns = itertools.repeat('A', 3)
>>> for n in ns:
...     print(n)
...
A
A
A

>>> natuals = itertools.count(1)
>>> ns = itertools.takewhile(lambda x: x <= 10, natuals)
>>> list(ns)
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

>>> for c in itertools.chain('ABC', 'XYZ'):
...     print(c)
# 迭代效果：'A' 'B' 'C' 'X' 'Y' 'Z'

>>> for key, group in itertools.groupby('AAABBBCCAAA'):
...     print(key, list(group))
...
A ['A', 'A', 'A']
B ['B', 'B', 'B']
C ['C', 'C']
A ['A', 'A', 'A']

>>> for key, group in itertools.groupby('AaaBBbcCAAa', lambda c: c.upper()):
...     print(key, list(group))
...
A ['A', 'a', 'a']
B ['B', 'B', 'b']
C ['c', 'C']
A ['A', 'A', 'a']

# -*- coding: utf-8 -*-
import itertools


def pi(N):
    ' 计算pi的值 '
    # step 1: 创建一个奇数序列: 1, 3, 5, 7, 9, ...
    odd_num = itertools.count(start = 1, step = 2)
    # step 2: 取该序列的前N项: 1, 3, 5, 7, 9, ..., 2*N-1.
    firstN = itertools.takewhile(lambda x: x <= 2*N-1, odd_num)
    # step 3: 添加正负符号并用4除: 4/1, -4/3, 4/5, -4/7, 4/9, ...
    firstN_devided4 = [4/val if i%2 == 0 else -4/val for i,val in enumerate(firstN)]
    # step 4: 求和:
    return sum(firstN_devided4)


# 测试:
print(pi(10))
print(pi(100))
print(pi(1000))
print(pi(10000))
assert 3.04 < pi(10) < 3.05
assert 3.13 < pi(100) < 3.14
assert 3.140 < pi(1000) < 3.141
assert 3.1414 < pi(10000) < 3.1415
print('ok')e

class Query(object):

    def __init__(self, name):
        self.name = name

    def __enter__(self):
        # 返回with as var语句中的var
        print('Begin')
        return self
    
    def __exit__(self, exc_type, exc_value, traceback):
        if exc_type:
            print('Error')
        else:
            print('End')
    
    def query(self):
        print('Query info about %s...' % self.name)

with Query('Bob') as q:
    q.query()

Begin
Query info about Bob...
End

from contextlib import contextmanager

class Query(object):

    def __init__(self, name):
        self.name = name

    def query(self):
        print('Query info about %s...' % self.name)

@contextmanager
def create_query(name):
    print('Begin')
    q = Query(name)
    yeild q
    print('End')

with create_query('Bob') as q:
    q.query()

@contextmanager
def locked(lock):
    lock.acquire()
    try:
        yield
    finally:
        lock.release()

with locked(myLock):
    #代码执行到这里时，myLock已经自动上锁
    pass
    #执行完后会，会自动释放锁

@contextmanager
def myopen(filename, mode="r"):
    f = open(filename,mode)
    try:
        yield f
    finally:
        f.close()

with myopen("test.txt") as f:
    for line in f:
        print(line)

@contextmanager
def transaction(db):
    db.begin()
    try：
        yield 
    except:
        db.rollback()
        raise
    else:
        db.commit()

with transaction(mydb):
    mydb.cursor.execute(sql)
    mydb.cursor.execute(sql)
    mydb.cursor.execute(sql)
    mydb.cursor.execute(sql)

@contextmanager
def tag(name):
    print("<%s>" % name)
    yield
    print("</%s>" % name)

with tag("h1"):
    print("hello")
    print("world")

<h1>
hello
world
</h1>

with mgr1:
    with mgr2:
        ...
        with mgrn:
            pass

from contextlib import contextmanager
from contextlib import nested
from contextlib import closing

@contextmanager
def my_context(name):
    print("enter")
    try:
        yield name
    finally:
        print("exit")

#使用nested函数来调用多个管理器
print("---------使用nested函数调用多个管理器-----------")
with nested(my_context("管理器一"), my_context("管理器二"),my_context("管理器三")) as (m1,m2,m3):
    print(m1)
    print(m2)
    print(m3)

#直接使用with来调用调用多个管理器
print("---------使用with调用多个管理器-----------")
with my_context("管理器一") as m1, my_context("管理器二") as m2, my_context("管理器三") as m3:
    print(m1)
    print(m2)
    print(m3)

---------使用nested函数调用多个管理器-----------
enter
enter
enter
管理器一
管理器二
管理器三
exit
exit
exit
---------使用with调用多个管理器-----------
enter
enter
enter
管理器一
管理器二
管理器三
exit
exit
exit

1 class closing(object):
18     def __init__(self, thing):
19         self.thing = thing
20     def __enter__(self):
21         return self.thing
22     def __exit__(self, *exc_info):
23         self.thing.close()

import urllib, sys
from contextlib import closing

with closing(urllib.urlopen('http://www.yahoo.com')) as f:
    for line in f:
        sys.stdout.write(line)

from urllib import request

with request.urlopen('https://api.douban.com/v2/book/2129650') as f:
    data = f.read()
    print('Status:', f.status, f.reason)
    for k, v in f.getheaders():
        print('%s: %s' % (k, v))
    print('Data:', data.decode('utf-8'))

Status: 200 OK
Server: nginx
Date: Tue, 26 May 2015 10:02:27 GMT
Content-Type: application/json; charset=utf-8
Content-Length: 2049
Connection: close
Expires: Sun, 1 Jan 2006 01:00:00 GMT
Pragma: no-cache
Cache-Control: must-revalidate, no-cache, private
X-DAE-Node: pidl1
Data: {"rating":{"max":10,"numRaters":16,"average":"7.4","min":0},"subtitle":"","author":["廖雪峰编著"],"pubdate":"2007-6",...}

from urllib import request

req = request.Request('http://www.douban.com/')
req.add_header('User-Agent', 'Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 Mobile/10A5376e Safari/8536.25')
with request.urlopen(req) as f:
    print('Status:', f.status, f.reason)
    for k, v in f.getheaders():
        print('%s: %s' % (k, v))
    print('Data:', f.read().decode('utf-8'))

...
    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0">
    <meta name="format-detection" content="telephone=no">
    <link rel="apple-touch-icon" sizes="57x57" href="http://img4.douban.com/pics/cardkit/launcher/57.png" />
...

from urllib import request, parse

print('Login to weibo.cn...')
email = input('Email: ')
passwd = input('Password: ')
login_data = parse.urlencode([
    ('username', email),
    ('password', passwd),
    ('entry', 'mweibo'),
    ('client_id', ''),
    ('savestate', '1'),
    ('ec', ''),
    ('pagerefer', 'https://passport.weibo.cn/signin/welcome?entry=mweibo&r=http%3A%2F%2Fm.weibo.cn%2F')
])

req = request.Request('https://passport.weibo.cn/sso/login')
req.add_header('Origin', 'https://passport.weibo.cn')
req.add_header('User-Agent', 'Mozilla/6.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/8.0 Mobile/10A5376e Safari/8536.25')
req.add_header('Referer', 'https://passport.weibo.cn/signin/login?entry=mweibo&res=wel&wm=3349&r=http%3A%2F%2Fm.weibo.cn%2F')

with request.urlopen(req, data=login_data.encode('utf-8')) as f:
    print('Status:', f.status, f.reason)
    for k, v in f.getheaders():
        print('%s: %s' % (k, v))
    print('Data:', f.read().decode('utf-8'))

Status: 200 OK
Server: nginx/1.2.0
...
Set-Cookie: SSOLoginState=1432620126; path=/; domain=weibo.cn
...
Data: {"retcode":20000000,"msg":"","data":{...,"uid":"1658384301"}}

...
Data: {"retcode":50011015,"msg":"\u7528\u6237\u540d\u6216\u5bc6\u7801\u9519\u8bef","data":{"username":"example@python.org","errline":536}}

proxy_handler = urllib.request.ProxyHandler({'http': 'http://www.example.com:3128/'})
proxy_auth_handler = urllib.request.ProxyBasicAuthHandler()
proxy_auth_handler.add_password('realm', 'host', 'username', 'password')
opener = urllib.request.build_opener(proxy_handler, proxy_auth_handler)
with opener.open('http://www.example.com/login.html') as f:
    pass

from xml.parsers.expat import ParserCreate

class DefaultSaxHandler(object):
    def start_element(self, name, attrs):
        print('sax:start_element: %s, attrs: %s' % (name, str(attrs)))

    def end_element(self, name):
        print('sax:end_element: %s' % name)

    def char_data(self, text):
        print('sax:char_data: %s' % text)

xml = r'''<?xml version="1.0"?>
<ol>
    <li><a href="/python">Python</a></li>
    <li><a href="/ruby">Ruby</a></li>
</ol>
'''

handler = DefaultSaxHandler()
parser = ParserCreate()
parser.StartElementHandler = handler.start_element
parser.EndElementHandler = handler.end_element
parser.CharacterDataHandler = handler.char_data
parser.Parse(xml)

L = []
L.append(r'<?xml version="1.0"?>')
L.append(r'<root>')
L.append(encode('some & data'))
L.append(r'</root>')
return ''.join(L)

from html.parser import HTMLParser
from html.entities import name2codepoint

class MyHTMLParser(HTMLParser):

    def handle_starttag(self, tag, attrs):
        print('<%s>' % tag)

    def handle_endtag(self, tag):
        print('</%s>' % tag)

    def handle_startendtag(self, tag, attrs):
        print('<%s/>' % tag)

    def handle_data(self, data):
        print(data)

    def handle_comment(self, data):
        print('<!--', data, '-->')

    def handle_entityref(self, name):
        print('&%s;' % name)

    def handle_charref(self, name):
        print('&#%s;' % name)

parser = MyHTMLParser()
parser.feed('''<html>
<head></head>
<body>
<!-- test html parser -->
    <p>Some <a href=\"#\">html</a> HTML&nbsp;tutorial...<br>END</p>
</body></html>''')