Right now there is a significant single-threaded performance cost. Somewhere from 30-50%. Part of what my colleague Ken Jin and others are working on is getting back some of that lost performance by applying some optimizations. Expect single-threaded performance to improve for Python 3.14 next year.

Python 3 的支援週期

Python 的支援週期在「Status of Python versions」這頁可以看到，只看 Python 3 的部分的話，可以看出來從 3.2 之後的版本都是固定五年：

Python 上的 reals 套件 (需要 3.10+ 以上才能裝)

It allows you to compute approximations to an arbitrary degree of precision, and, contrary to most other libraries, guarantees that all digits it displays are correct.

Constants: pi, e, phi
Functions related to powers: sqrt, exp, log
Operators: negation, addition, subtraction, multiplication, division, powers
Trigonometric functions: sin, sinh, csc, csch, cos, cosh, sec, sech, tan, tanh, cot, coth

`>>> from reals import sqrt`

```>>> sqrt2 = sqrt(2)
>>> sqrt2
<reals._real.Real object at 0x10d182560 (approximate value: 1.41421)>```
```>>> sqrt2.evaluate(10)
'1.4142135624'
>>> '{:.10f}'.format(sqrt2)
'1.4142135624'
>>> sqrt2.to_decimal(10)
Decimal('1.4142135624')```

Trac 開發版 1.5.1 對 Python 3 的說明

Trac 開發版 1.5.1 的 Change Log 裡可以看到說明：

This will be the only release in the 1.5.x release line that supports Python 2.7. Future releases will support Python 3.5+.

Python 3.7+ 保證 dict 內容的順序

Changed in version 3.7: Dictionary order is guaranteed to be insertion order. This behavior was an implementation detail of CPython from 3.6.

用 pipsi 管 Python 的 command line 工具...

pipsi 是將套件用 virtualenv 包起來，讓使用者在用的時候不會受到其他環境的干擾。我是拿來跟系統的 `python3` (目前在 Ubuntu 16.04 上是指到 3.5.1) 使用，所以安裝 pipsi 時先切到 system 再透過 `python3` 安裝 (讓他偵測到系統的 `python3`)：

```\$ pyenv shell system
\$ which python3
\$ curl https://raw.githubusercontent.com/mitsuhiko/pipsi/master/get-pipsi.py | python3```

`\$ pipsi install awscli`