function processOptions(opts) {
  opts = opts || {};
  var options = {};

  options.harmony = opts.harmony;
  options.stripTypes = opts.stripTypes;
  options.sourceMap = opts.sourceMap;
  options.filename = opts.sourceFilename;

  if (opts.es6module) {
    options.sourceType = 'module';
  }
  if (opts.nonStrictEs6module) {
    options.sourceType = 'nonStrictModule';
  }

  // Instead of doing any fancy validation, only look for 'es3'. If we have
  // that, then use it. Otherwise use 'es5'.
  options.es3 = opts.target === 'es3';
  options.es5 = !options.es3;

  return options;
}
Only copy the values that we need. We'll do some preprocessing to account for
converting command line flags to options that jstransform can actually use.