f = open("data.txt", "r")
data = f.read()
f.close()

with open("data.txt", "r") as f:
    data = f.read()

with open("output.txt", "w") as f:
    f.write("Hello, Python!")

from itertools import groupby
from operator import itemgetter

data = [
    {"user": "alice", "score": 8},
    {"user": "bob",   "score": 5},
    {"user": "alice", "score": 7},
    {"user": "bob",   "score": 9},
]

# Сортируем по ключу
data.sort(key=itemgetter("user"))

# Группируем и считаем средний балл
for user, items in groupby(data, key=itemgetter("user")):
    scores = [i["score"] for i in items]
    print(user, "avg score:", sum(scores) / len(scores))

import time
import threading
from collections import OrderedDict

class TTLLRUCache:
    def __init__(self, maxsize=1024):
        self.maxsize = maxsize
        self._cache = OrderedDict()
        self._lock = threading.RLock()
        self._expiry_times = {}

    def get(self, key):
        with self._lock:
            if key not in self._cache:
                return None
            
            # Ленивое удаление просроченного ключа
            if self._is_expired(key):
                self._delete(key)
                return None
            
            # Обновляем порядок использования (LRU)
            self._cache.move_to_end(key)
            return self._cache[key]

    def set(self, key, value, ttl=None):
        with self._lock:
            # Вытеснение старых записей при достижении лимита
            if len(self._cache) >= self.maxsize:
                self._evict()
            
            self._cache[key] = value
            self._cache.move_to_end(key)
            self._expiry_times[key] = time.time() + ttl if ttl else None

    def delete(self, key):
        with self._lock:
            self._delete(key)

    def _delete(self, key):
        self._cache.pop(key, None)
        self._expiry_times.pop(key, None)

    def clear(self):
        with self._lock:
            self._cache.clear()
            self._expiry_times.clear()

    def _is_expired(self, key):
        expiry = self._expiry_times.get(key)
        return expiry is not None and expiry < time.time()

    def _evict(self):
        # Сначала удаляем просроченные ключи
        expired_keys = [k for k in self._cache if self._is_expired(k)]
        for k in expired_keys:
            self._delete(k)
        
        # Если после этого кэш всё ещё полон, применяем LRU
        if len(self._cache) >= self.maxsize:
            self._cache.popitem(last=False)

    def __contains__(self, key):
        with self._lock:
            if key not in self._cache:
                return False
            if self._is_expired(key):
                self._delete(key)
                return False
            return True

def counter(func):
    count = 0
    
    def wrapper(*args, **kwargs):
        nonlocal count
        count += 1
        print(f"Функция {func.__name__} вызвана {count} раз")
        return func(*args, **kwargs)
    
    return wrapper

@counter
def greet(name):
    return f"Привет, {name}!"

print(greet("Анна"))
print(greet("Пётр"))

callbacks = [lambda: print(i) for i in range(3)]

for f in callbacks:
    f()

callbacks = [lambda i=i: print(i) for i in range(3)]
for f in callbacks:
    f()  # 0 1 2

def make_printer(i):
    def _f():
        print(i)
    return _f

callbacks = [make_printer(i) for i in range(3)]
for f in callbacks:
    f()  # 0 1 2

from functools import partial

callbacks = [partial(print, i) for i in range(3)]
for f in callbacks:
    f()  # 0 1 2

import threading

for i in range(3):
    # ПЛОХО: замкнёт одно и то же i
    # threading.Timer(1, lambda: print(i)).start()

    # ХОРОШО: привяжем значение сразу
    threading.Timer(1, lambda i=i: print(i)).start()

import os
import urllib.request

from concurrent.futures import ThreadPoolExecutor, as_completed

def downloader(url):
    """Скачивает указанный URL и сохраняет его на диск"""
    req = urllib.request.urlopen(url)
    filename = os.path.basename(url)
    ext = os.path.splitext(url)[1]
    if not ext:
        raise RuntimeError('URL не содержит расширения')

    with open(filename, 'wb') as file_handle:
        while True:
            chunk = req.read(1024)
            if not chunk:
                break
            file_handle.write(chunk)

    return f'Загрузка завершена: {filename}'

def main(urls):
    """Создаёт пул потоков и скачивает указанные файлы"""
    with ThreadPoolExecutor(max_workers=5) as executor:
        futures = [executor.submit(downloader, url) for url in urls]
        for future in as_completed(futures):
            print(future.result())

if __name__ == '__main__':
    urls = [
        "http://www.irs.gov/pub/irs-pdf/f1040.pdf",
        "http://www.irs.gov/pub/irs-pdf/f1040a.pdf",
        "http://www.irs.gov/pub/irs-pdf/f1040ez.pdf",
        "http://www.irs.gov/pub/irs-pdf/f1040es.pdf",
        "http://www.irs.gov/pub/irs-pdf/f1040sb.pdf"
    ]
    main(urls)