text: var path = require('path');
  
  exports.base = function() {
    return {
      filename: '',
      filenameRelative: '',
      sourceMap: true,
      sourceRoot: '',
      moduleRoot: path.resolve('src').replace(/\\/g, '/'),
      moduleIds: false,
      comments: false,
      compact: false,
      code: true,
      presets: [['es2015', { loose: true }], 'stage-1'],
      plugins: [
        'syntax-flow',
        'transform-decorators-legacy',
        'transform-flow-strip-types',
      ]
    };
  };
  
  exports.commonjs = function() {
    var options = exports.base();
    options.plugins.push('transform-es2015-modules-commonjs');
    return options;
  };
  
  exports.amd = function() {
    var options = exports.base();
    options.plugins.push('transform-es2015-modules-amd');
    return options;
  };
  
  exports.system = function() {
    var options = exports.base();
    options.plugins.push('transform-es2015-modules-systemjs');
    return options;
  };
  
  exports.es2015 = function() {
    var options = exports.base();
    options.presets = ['stage-1'];
    return options;
  };
  