then you may need to force rustbuild to use an older version. This can be done
by manually calling the appropriate vcvars file before running the bootstrap.
-```
-CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
-python x.py build
+```batch
+> CALL "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\amd64\vcvars64.bat"
+> python x.py build
```
#### Specifying an ABI