Python 2.7.9 and later (on the python2 series), and Python 3.4 and later include pip (pip3 for Python 3) by default.[5]
pip is a recursive acronym for "Pip Installs Packages".[6]
和GNU的定义差不多，递归式的定义
pip 的具体含义
原文：https://www.cnblogs.com/zdj8023/p/10853268.html
