text: var fs    = require('fs');
  var path  = require('path');
  var vm    = require('vm');
  
  var jsdir = path.join(__dirname, '..', 'static', 'js');
  var sandbox = vm.createContext();
  
  function execFile(filename, sandbox) {
    var filepath = path.join(jsdir, filename);
    var code = fs.readFileSync(filepath).toString();
    vm.runInContext(code, sandbox);
  }
  
  execFile('tile.js', sandbox);
  execFile('grid.js', sandbox);
  execFile('game_manager.js', sandbox);
  
  exports.Tile = sandbox.Tile;
  exports.Grid = sandbox.Grid;
  exports.GameManager = sandbox.GameManager;
  exports.Direction = sandbox.Direction;
  