# Очистка всех элементов листа:
>>> lst = [1, 2, 3, 4, 5]
>>> del lst[:]
>>> lst
[]

# Замена всех элементов листа
# без создания нового объекта:
>>> a = lst
>>> lst[:] = [7, 8, 9]
>>> lst
[7, 8, 9]
>>> a
[7, 8, 9]
>>> a is lst
True

# Создание копии листа:
>>> b = lst[:]
>>> b
[7, 8, 9]
>>> b is lst
False

def myfunc(x, y, z):
    print(x, y, z)

tuple_vec = (1, 0, 1)
dict_vec = {'x': 1, 'y': 0, 'z': 1}

>>> myfunc(*tuple_vec)
1, 0, 1

>>> myfunc(**dict_vec)
1, 0, 1

>>> import collections
>>> c = collections.Counter('helloworld’)

>>> c
Counter({'l': 3, 'o': 2, 'e': 1, 'd': 1, 'h': 1, 'r': 1, 'w': 1})

>>> c.most_common(3)
[('l', 3), ('o', 2), ('e', 1)]

>>> import itertools
>>> for p in itertools.permutations('ABCD'):
...     print(p)

('A', 'B', 'C', 'D')
('A', 'B', 'D', 'C')
('A', 'C', 'B', 'D')
('A', 'C', 'D', 'B')
('A', 'D', 'B', 'C')
('A', 'D', 'C', 'B')
('B', 'A', 'C', 'D')
('B', 'A', 'D', 'C')
('B', 'C', 'A', 'D')
('B', 'C', 'D', 'A')
('B', 'D', 'A', 'C')
('B', 'D', 'C', 'A')
('C', 'A', 'B', 'D')
('C', 'A', 'D', 'B')
('C', 'B', 'A', 'D')
('C', 'B', 'D', 'A')
('C', 'D', 'A', 'B')
('C', 'D', 'B', 'A')
('D', 'A', 'B', 'C')
('D', 'A', 'C', 'B')
('D', 'B', 'A', 'C')
('D', 'B', 'C', 'A')
('D', 'C', 'A', 'B')
('D', 'C', 'B', ‘A’)

from itertools import islice

def fib():
    a, b = 0, 1
    while True:
        yield b
        a, b = b, a + b
…
In : list(islice(fib(), 6))
Out: [1, 1, 2, 3, 5, 8]

from functools import reduce

In : reduce(lambda x, y: x*y, [1, 2, 3, 4, 5, 6])
Out: 720

import operator
import functools

In : functools.reduce(operator.mul, [1, 2, 3, 4, 5, 6], 1)
Out: 720

import numpy as np

In : np.prod(np.array([1, 2, 3, 4, 5, 6]))
Out: 720

In[1]: qwe = ‘qwe’
In[2]: qwe[0] = ‘a’
In[3]: print(qwe)

a = ‘a’
a += ‘b’

int result = 0;
for(int i=0; i<100; ++i){
    result += i;
}

result = 0
for i in range(100):
    result += i

x = 4
x = “four”

int x = 4;
x = “four” // сбой

struct _longobject {
    long ob_refcnt;
    PyTypeObject *ob_type;
    size_t ob_size;
    long ob_digit[1];

>>> import ipaddress

>>> ipaddress.ip_address('192.168.1.2')
IPv4Address('192.168.1.2')

>>> ipaddress.ip_address('2001:af3::')
IPv6Address('2001:af3::’)

for i in range(len(digits) - 1, -1, -1):
        for c in str((double + 1) * int(digits[i])):
            total += int(c)
        double = (double + 1) % 2

def validate_card(card_num):
    """
    Input: Card number, integer or string
    Output: Valid?, boolean
    """
    double = 0
    total = 0

    digits = str(card_num)

    for i in range(len(digits) - 1, -1, -1):
        for c in str((double + 1) * int(digits[i])):
            total += int(c)
        double = (double + 1) % 2

    return (total % 10) == 0

In : {True: 'да', 1: 'нет', 1.0: 'возможно'}
Out: ?

>>> class BaseClass: pass
>>> class SubClass(BaseClass): pass

>>> issubclass(SubClass, BaseClass)
True
>>> issubclass(SubClass, object)
True
>>> issubclass(BaseClass, SubClass)
False

def contains(haystack, needle):
    """
    Бросаем ValueError если needle не
    находится в haystack.
    """
    for item in haystack:
        if item == needle:
            break
    else:
        # else здесь выполнится только
        # если цикл не будет прерван break
        raise ValueError('Needle not found')

>>> contains([23, 'needle', 0xbadc0ffee], 'needle')
None

>>> contains([23, 42, 0xbadc0ffee], 'needle')
ValueError: "Needle not found"

def better_contains(haystack, needle):
    for item in haystack:
        if item == needle:
            return
    raise ValueError('Needle not found')

if needle not in haystack:
    raise ValueError('Needle not found’)