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’)

def get_min(x, df, gamma):
    eps = 1e-6
    max_iters = 10000
    for _ in range(max_iters):
        curr_x = x
        x = curr_x - gamma * df(curr_x)
        if abs(x - curr_x) < eps:
            break

    return x

df = lambda x: 4 * x**3 - 9 * x**2
res = get_min(6, df, 0.01)
print(f’Minimum at {res:.2f}’)

Out[1]: Minimum at 2.25

>>> lst = ['a', 'a', 'a']

>>> len(set(lst)) == 1
True

>>> all(x == lst[0] for x in lst)
True

>>> lst.count(lst[0]) == len(lst)
True

>>> def f(a, b, *, c='x', d='y', e='z'):
...     return 'Hello'

>>> f(1, 2, 'p', 'q', 'v')
TypeError: 
"f() takes 2 positional arguments but 5 were given"

>>> f(1, 2, c='p', d='q',e='v')
'Hello’

import itertools

m_dict = {‘1’:’1’, ‘2’:’2’, ‘3’:’3’, ‘4’:’4’, ‘5’:’5’}
m_dict = dict(itertools.islice(m_dict.items(), 3))

Out[0]: {‘1’:’1’, ‘2’:’2’, ‘3’:’3’}

m_dict1 = {‘1’:’1’, ‘2’:’2’}
m_dict2 = {‘3’:’3’, ‘4’:’4’}
m_dict = dict(m_dict1, **m_dict2)

Out[0]: {‘1’:’1’, ‘2’:’2’, ‘3’:’3’, ‘4’:’4’}