docs: function processDeps(queue, collection, callback, errBack) {
    return errTo(errBack, function(packages) {
      var deps;
  
      packages.forEach(function(pkg) {
        // add the package to the collection of processed packages
        addPackage(collection, pkg);
  
        // if the module has dependencies, add them to the processing queue
        // unless they have been already processed
        mapDependencies(pkg.dependencies).forEach(function(dep) {
          if (!isDuplicate(collection[dep.name], dep.version)) {
            addToQueue(queue, dep);
          }
        });
      });
  
      callback(queue);
    });
  }