好奇，想一探究竟。安装就出点小问题，win7,64位，一直卡在这里不动了？
只好取消。第二天安装仍是如此。
于是下载Windows6.1-KB2999226-x64.msu，安装，仍卡顿不动；
于是找各种解决办法，只有这个有用：
http://abcblog.lofter.com/ 感谢
http://stackoverflow.com/questions/31536606/while-installing-vc-redist-x64-exe-getting-error-failed-to-configure-per-machi
This is because the OS failed to install the required update Windows8.1-KB2999226-x64.msu.
However, you can install it by extracting that update to a folder (e.g. XXXX), and execute following cmdlet. You can find the Windows8.1-KB2999226-x64.msu at below.
C:\ProgramData\Package Cache\469A82B09E217DDCF849181A586DF1C97C0C5C85\packages\Patch\amd64\Windows8.1-KB2999226-x64.msu
copy this file to a folder you like, and
Create a folder XXXX in that and execute following commands from Admin command propmt
wusa.exe Windows8.1-KB2999226-x64.msu /extract:XXXX
DISM.exe /Online /Add-Package /PackagePath:XXXX\Windows8.1-KB2999226-x64.cab
vc_redist.x64.exe /repair last command need not be run. Just execute exe once again.
this worked for me.
再安装python-3.5.2-amd64.exe，成功。
