spaghetti.js

var start = function(path, options, extra, callback) {
  fs.exists(path, function(exists) {
    if (!exists) {
      return cb(new Error('File ' + path + 'does not exist'));
    }

    if (typeof extra === 'function') {
      callback = extra;
      extras = [];
    } else if (typeof options === 'function') {
      callback = options;
      extras = [];
      options = {};
    }

    var exec_options = [];
    var key;
    for (key in options) {
      exec_options.push(key);
      exec_options.push(options[key]);
    }

    exec_options.push(path);

    exec_options.concat(extra);

    command('vmrun ' + exec_options.join(' '), callback);
  });
};