code: function (options, iterationInfo, modules) {
  
          // Ignore explicitly excluded directories
          if (options.excludeDirs) {
              var match = iterationInfo.fileName.match(options.excludeDirs);
              if (match)
                  return;
          }
  
          // Recursively call requireAll on each child directory
          var subIterationInfo = _.clone(iterationInfo);
          ++subIterationInfo.depth;
          subIterationInfo.dirName = iterationInfo.absoluteFullPath;
  
          //process subtree recursively
          var subTreeResult = doInterations(options, subIterationInfo);
  
          //omit empty dirs
          if (_.isEmpty(subTreeResult))
              return;
  
          //add to the list or to the subtree
          if (options.mode === 'list') {
              //check uniqueness
              _.forEach(subTreeResult, function (value, index) {
                  if (options.useVersions === true) {
                      modules[index] = modules[index] || {};
                      _.forEach(value, function (versionValue, versionIndex) {
                          if (modules[index][versionIndex])
                              throw new Error("Identity '" + index + "' with version '" + versionIndex + "' is already registered by module at '" + modules[index][versionIndex].absoluteFullPath + "'");
                          modules[index][versionIndex] = versionValue;
                      });
                  }
                  else {
                      if (modules[index])
                          throw new Error("Identity '" + index + "' is already registered by module at '" + modules[index].absoluteFullPath + "'");
                      modules[index] = value;
                  }
              })
          }
          else if (options.mode === 'tree') {
              if (options.markDirectories !== false) {
                  subTreeResult.isDirectory = true;
              }
  
              var identity = generateIdentity(options, iterationInfo);
              modules[identity] = subTreeResult;
          }
          else
              throw new Error('Unknown mode');
      }
docs: Processes one directory level
  @param options :: general options
  @param iterationInfo :: iteration options
  @param modules :: object in which output will be loaded