PyExecJS is a porting of ExecJS from Ruby. PyExecJS automatically picks the
best runtime available to evaluate your JavaScript program.

Supported runtimes
* PyV8 - A python wrapper for Google V8 engine,
* Node.js
* Apple JavaScriptCore - Included with Mac OS X
* Mozilla SpiderMonkey
* Microsoft Windows Script Host (JScript)
* SlimerJS
* Nashorn - Included with Oracle Java 8