code: function (modNames, runtime, stack, errorList, cache) {
              // for debug. prevent circular dependency
              stack = stack || [];
              // for efficiency. avoid duplicate non-attach check
              cache = cache || {};
              var i,
                  s = 1,
                  l = modNames.length,
                  stackDepth = stack.length;
              for (i = 0; i < l; i++) {
                  s = s && Utils.attachModRecursively(modNames[i], runtime, stack, errorList, cache);
                  stack.length = stackDepth;
              }
              return s;
          }
docs: attach modules and their dependency modules recursively
  @param {String[]} modNames module names
  @param runtime Module container, such as KISSY
  @param {String[]} [stack] stack for detecting circular dependency
  @param {Array} [errorList] errors when attach mods
  @param {Object} [cache] cached modules to avoid duplicate check
  @returns whether success attach all modules