Mac 安装gevent

直接运行 pip install gevent 安装必然会报错，正确的做法：

安装xcode

xcode-select --install

再次运行
pip install gevent安装成功。

mac126:Desktop mac126$ pip3 install gevent
Collecting gevent
  Using cached https://files.pythonhosted.org/packages/6c/49/681ec1026fe0313d1c6f00a58416f9ade121911f2fd55023e3e7cbd7803f/gevent-1.4.0-cp36-cp36m-macosx_10_6_intel.whl
Collecting greenlet>=0.4.14; platform_python_implementation == "CPython" (from