Using grunt to run python koans on change

Gruntfile.js

module.exports = function(grunt) {
	"use strict";
	grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    watch: {
		files: ['./koans/*.py'],
		tasks: ['pythonrun']
	}
    });
    
    grunt.loadNpmTasks('grunt-contrib-watch');

    grunt.registerTask('pythonrun',"runs the python comand",function(){

        var exec = require('child_process').exec;
        var cb = this.async();
        exec('python.exe ./contemplate_koans.py', {cwd: '.'}, function(err, stdout, stderr) {
            grunt.log.write(stdout);
            cb();
        });     
        
    });

};

package.json

{
  "name": "learnPython",
  "version": "0.0.0",
  "description": "just for grunt",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "https://github.com/srgrn/python_koans.git"
  },
  "author": "",
  "license": "BSD",
  "bugs": {
    "url": "https://github.com/srgrn/python_koans/issues"
  },
  "devDependencies": {
    "grunt-contrib-watch": "~0.5.3",
    "grunt": "~0.4.2",
    "grunt-contrib-commands": "~0.1.6"
  }
}