code: function (modName) {
              var mods = Env.mods,
                  status,
                  m = mods[modName];
              status = m.status;
              // attached or circular dependency
              if (status >= ATTACHING) {
                  return;
              }
              m.status = ATTACHING;
              if (m.cjs) {
                  // commonjs format will call require in module code again
                  Utils.attachMod(m);
              } else {
                  Utils.attachModsRecursively(m.getNormalizedRequires());
                  Utils.attachMod(m);
              }
          }
docs: attach module and its dependency modules recursively
  @param {String} modName module name