old_contents: var exec = require('child_process').exec;
  
  exports['read.js:compress'] = function (srcPath, callback) {
    console.error('js read compress');
    // uitl.isMinified
    exec('uglifyjs ' + srcPath, function (err, stdout, stderr) {
      callback(err, stdout);
    });
  };
  
  exports['each.js'] = function (content, callback) {
    console.error('js each');
    callback(null, content);
    // TODO return false to stop chane
  };
  
  exports['join.js'] = function (files, callback) {
    console.error('js join');
    callback(null, files.join(';\n\n\n'));
  };
  
  //exports['join'] = function (files, callback) {
    
  //};
new_contents: var exec = require('child_process').exec;
  
  exports['read.js:compress'] = function (srcPath, callback) {
    // uitl.isMinified
    exec('uglifyjs ' + srcPath, function (err, stdout, stderr) {
      callback(err, stdout);
    });
  };
  
  // exports['each.js'] = function (content, callback) {
  //   callback(null, content);
  //   // third argument stop: true to stop chain
  //   // callback(null, content, true)
  // };
  
  exports['join.js'] = function (files, callback) {
    callback(null, files.join(';\n\n\n'));
  };
subject: comment out each