-- Database: MySQL
-- Setup before test
create table test (id int primary key, value int) engine=innodb;
insert into test (id, value) values (1, 10), (2, 20);
-- Test the "read uncommited" isolation level on the "Intermediate Reads" (G1b) anomaly
set session transaction isolation level read uncommitted; begin; -- T1
set session transaction isolation level read uncommitted; begin; -- T2
update test set value = 101 where id = 1; -- T1
select * from test; -- T2. Shows 1 => 101
update test set value = 11 where id = 1; -- T1
commit; -- T1
select * from test; -- T2. Now shows 1 => 11
commit; -- T2
-- Result: doesn't prevent G1b

>>> import feedparser
>>> d = feedparser.parse('http://feedparser.org/docs/examples/atom10.xml')
>>> d.etag
'"6c132-941-ad7e3080"'
>>> d2 = feedparser.parse('http://feedparser.org/docs/examples/atom10.xml', etag=d.etag)
>>> d2.feed
{}
>>> d2.debug_message
'The feed has not changed since you last checked, so the server sent no data.  This is a feature, not a bug!'

def square(num: int) -> int:
    return num * num

def insert_data(insert_query: str, db_connection: DbConnectionType) -> int:
  db_connection.execute(insert_query)
  return True

import json
import os
from typing import Any, Dict
from aws_lambda_powertools.utilities.typing import LambdaContext  # нужно только для аннотации типа аргумента
import boto3
limit = os.getenv('LIMIT')
def handler_name(event: Dict[str: Any], context: LambdaContext):
    request_id = context.aws_request_id
    # Находим user_id во входящем событии
    user_id = event["user_id"]
    # Наша таблица на DynamoDB
    table = boto3.resource('dynamodb').Table('my_table')
    # Делаем update
    table.update_item(
        Key={'pkey': user_id},
        UpdateExpression='ADD requests :request_id',
        ConditionExpression='attribute_not_exists (requests) OR (size(requests) < :limit AND NOT contains(requests, :request_id))',
        ExpressionAttributeValues={
            ':request_id': {'S': request_id},
            ':requests': {'SS': [request_id]},
            ':limit': {'N': limit}
        }
    )
    # TODO: написать дальнейшую логику
    return {
        "statusCode": 200,
        "headers": {
            "Content-Type": "application/json"
        },
        "body": json.dumps({
            "status ": "success"
        })
    }

>>> import uuid
>>> str(uuid.uuid4())
'f50ec0b7-f960-400d-91f0-c42a6d44e3d0'
>>> str(uuid.uuid4())
'd15bed89-c0a5-4a72-98d9-5507ea7bc0ba'

import logging
import random
import sys
from tenacity import retry, stop_after_attempt, stop_after_delay, wait_exponential, retry_if_exception_type, before_log
logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)
logger = logging.getLogger(__name__)
@retry(
    stop=(stop_after_delay(10) | stop_after_attempt(5)),
    wait=wait_exponential(multiplier=1, min=4, max=10),
    retry=retry_if_exception_type(IOError),
    before=before_log(logger, logging.DEBUG)
)
def do_something_unreliable():
    if random.randint(0, 10) > 1:
        raise IOError("Broken sauce, everything is hosed!!!111one")
    else:
        return "Awesome sauce!"
print(do_something_unreliable.retry.statistics)