def setup_module(module):
def teardown_module(module):

@classmethod
def setup_clas(cls):
@classmethod
def teardown_class(cls):

def setup_method(self, method):
def teardown_method(self, method):

def setup_function(function):
def teardown_function(function):

import math

def compute_rmse(observed, ideal):
    total_err_2 = 0
    count = 0
    for got, wanted in zip(observed, ideal):
        err_2 = (got - wanted) ** 2
        if err_2 >= 1:  # Injected for pdb
            breakpoint()  # Breakpoint will trigger pdb 
        total_err_2 += err_2
        count += 1
    mean_err = total_err_2 / count
    rmse = math.sqrt(mean_err)
    return rmse

result = compute_rmse(
    [1.8, 1.7, 3.2, 6],
    [2, 1.5, 3, 5])
print(result)

import os
class MyObject:
    def __init__(self):
        self.data = os.urandom(100)

def get_data():
    values = []
    for _ in range(100):
        obj = MyObject()
        values.append(obj)
    return values

def run():
    deep_values = []
    for _ in range(100):
        deep_values.append(get_data())
    return deep_values

import tracemalloc
tracemalloc.start(10)  # Set stack depth
time1 = tracemalloc.take_snapshot()
x = run()
time2 = tracemalloc.take_snapshot()
stats = time2.compare_to(time1, 'lineno')
for stat in stats[:3]:
    print(stat)
>>>
t.py:4: size=2314 KiB (+2314 KiB), count=29993 (+29993), average=79 B
t.py:9: size=469 KiB (+469 KiB), count=10001 (+10001), average=48 B
t.py:10: size=82.8 KiB (+82.8 KiB), count=100 (+100), average=848 B

print(repr(some_func.__doc__))

$ python -m pydoc -p 1234
Server ready at http://localhost:1234/
Server commands: [b]rowser, [q]uit
server> b

from xxxx.xxxx import inspect as xxxx_inspect
from yyyy.yyyy import inspect as yyyy_inspect

__all__ = []
from . models import *
__all__ += models.__all__
from . utils import *
__all__ += utils.__all__

class RootError(Exception):
    pass
class InvalidValueError(RootError):
    pass
class InvalidLengthError(RootError):
    pass

def some_func(name, value):
    if len(name) >= 10:
        raise InvalidLengthError('name length must be 9 or less')
    if value < 0:
        raise InvalidValueError('value must be 0 or higher')
    return name + str(value)

class RootError(Exception):  # ルート
    pass
class ValueError(RootError):  # 中間
    pass
class NameError(RootError):  # 中間
    pass
...

import warnings
def require(name, value, default):
    if value is not None:
        return value
    warnings.warn(
        f'{name} will be required soon, update your code',
        DeprecationWarning,
        stacklevel=3)
    return default

def print_distance(speed, duration, *,
                   speed_units=None,
                   time_units=None,
                   distance_units=None):
    speed_units = require('speed_units', speed_units, 'mph')
    time_units = require('time_units', time_units, 'hours')
    distance_units = require('distance_units', distance_units, 'miles')

    norm_speed = convert(speed, speed_units)
    norm_duration = convert(duration, time_units)
    norm_distance = norm_speed * norm_duration
    distance = localize(norm_distance, distance_units)
    print(f'{distance} {distance_units}')

import contextlib
import io
fake_stderr = io.StringIO()
with contextlib.redirect_stderr(fake_stderr):
    print_distance(1000, 3,
                   speed_units='meters',
                   time_units='seconds')
print(fake_stderr.getvalue())
>>>
1.8641182099494205 miles
t.py:46: DeprecationWarning: distance_units will be required soon, update your code
  print_distance(1000, 3,

import warnings
print('begin')
warnings.warn('This usage is deprecated',
              DeprecationWarning)
print('done')
>>>
(blg) ~/Documents/AW/py/blg % python t.py  # 普通に起動
begin
t.py:3: DeprecationWarning: This usage is deprecated
  warnings.warn('This usage is deprecated',
done
(blg) ~/Documents/AW/py/blg % python -W error t.py  # エラーを指定
begin
Traceback (most recent call last):
  File "t.py", line 3, in <module>
    warnings.warn('This usage is deprecated',
DeprecationWarning: This usage is deprecated

warnings.simplefilter('ignore')
warnings.warn('How about this?')

import io
import logging
import warnings
fake_stderr = io.StringIO()
handler = logging.StreamHandler(fake_stderr)
formatter = logging.Formatter(
    '%(asctime)-15s WARNING] %(message)s')
handler.setFormatter(formatter)

logging.captureWarnings(True)
logger = logging.getLogger('py.warnings')
logger.addHandler(handler)
logger.setLevel(logging.DEBUG)

warnings.resetwarnings()
warnings.simplefilter('default')
warnings.warn('This will go to the logs output')

print(fake_stderr.getvalue())
>>>
2020-09-01 08:00:24,490 WARNING] t.py:17: UserWarning: This will go to the logs output
  warnings.warn('This will go to the logs output')

def subtract(a: int, b: int) -> int:
    return a - b

python -m mypy --strict t.py