10 Python tricks you'll actually use, 8 of them with zero installs (with the numbers)

brew install uv
uv venv -p 3.14
UV_NO_CACHE=1 uv pip install requests flask

cold install, pip vs uv

package        pip      uv   ratio
requests     0.86s   0.15s    5.7x
flask        0.94s   0.15s    6.4x
pandas       4.07s   0.59s    6.9x

python 3.14.6 both · caches off · 5 runs each, median · alternating order

brew install ruff
$ ruff check --no-cache --statistics . | head -12
94      C408    [ ] unnecessary-collection-call
84      SIM115  [ ] open-file-with-context-handler
42      BLE001  [ ] blind-except
25      PLW1510 [ ] subprocess-run-without-check
22      RUF100  [*] unused-noqa
14      I001    [-] unsorted-imports
12      FURB167 [-] regex-flag-alias
12      S110    [ ] try-except-pass
10      F401    [*] unused-import
 8      B023    [ ] function-uses-loop-variable
 5      EXE001  [ ] shebang-not-executable
 5      S112    [ ] try-except-continue
$ ruff check --no-cache . | tail -2
Found 349 errors.
[*] 62 fixable with the `--fix` option (99 hidden fixes can be enabled with the `--unsafe-fixes` option).

>>> x = 42
>>> print(f'{x=}')
x=42
>>> team = 'infra'
>>> print(f'{team=} {x*2=}')
team='infra' x*2=84

$ cat app.py
def score(user):
    base = user["points"] * 2
    breakpoint()
    return base + bonus(user)

def bonus(user):
    return 10 if user["team"] == "infra" else 0

print(score({"name": "mara", "team": "infra", "points": 41}))
$ python3 app.py
> /private/tmp/pydemo/app.py(3)score()
-> breakpoint()
(Pdb) p user
{'name': 'mara', 'team': 'infra', 'points': 41}
(Pdb) p base
82
(Pdb) c
92

$ cat crash.py
rows = [line.strip().split(",") for line in open("users.csv")]
header, data = rows[0], rows[1:]
total = sum(int(r[2]) for r in data)
print("total points:", total)
$ python3 -i crash.py
Traceback (most recent call last):
  File "/private/tmp/pydemo/crash.py", line 3, in
    total = sum(int(r[2]) for r in data)
  File "/private/tmp/pydemo/crash.py", line 3, in
    total = sum(int(r[2]) for r in data)
ValueError: invalid literal for int() with base 10: 'receipt-7'
>>> data[1]
['jon', 'web', 'receipt-7']
>>> header
['name', 'team', 'points']

$ python3 -m http.server 8000 2>/dev/null &
[1] 77428
$ curl -sI localhost:8000/orders.json | head -3
HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/3.14.6
Date: Tue, 01 Sep 2026 14:59:55 GMT
$ curl -s localhost:8000/orders.json | head -c 80
{"orders":[{"id":9174,"user":"mara","items":[{"sku":"KB-01","qty":2,"price":39.5
$ kill %1

$ cat orders.json | python3 -m json.tool
{
    "orders": [
        {
            "id": 9174,
            "user": "mara",
            "items": [
                {
                    "sku": "KB-01",
                    "qty": 2,
                    "price": 39.5
                },
                ...
            ],
            "status": "shipped"
        },
        ...
    ],
    "count": 2
}

$ python3 -m timeit 'sum(range(1000))'
100000 loops, best of 5: 3.7 usec per loop
$ python3 -m timeit 'sum(range(100000))'
500 loops, best of 5: 425 usec per loop

$ python -X importtime -c 'import pandas' 2>&1 | tee it.log | tail -6
import time:       386 |        386 |     pandas.io.sql
import time:       145 |        145 |     pandas.io.xml
import time:       104 |       4290 |   pandas.io.api
import time:        73 |         73 |   pandas.util._tester
import time:        58 |         58 |   pandas._version_meson
import time:       392 |     187650 | pandas

$ cat slow_logs.py
import time

for step in ["load config", "connect db", "warm cache", "start worker", "ready"]:
    print(f"[boot] {step}")
    time.sleep(0.8)
$ python3 slow_logs.py | cat        # all five lines appear at once, at the end
$ python3 -u slow_logs.py | cat     # one line every 0.8 s, as they happen

brew install uv
uv venv -p 3.14
uv pip install requests flask
brew install ruff
ruff check --no-cache .
print(f'{x=}')
breakpoint()
python3 -i app.py
python3 -m http.server 8000
python3 -m json.tool
python3 -m timeit 'sum(range(1000))'
python3 -X importtime app.py
python3 -u app.py