code: function makeArgCallback(manager, i) {
              return function (value) {
                  //Only do the work if it has not been done
                  //already for a dependency. Cycle breaking
                  //logic in forceExec could mean this function
                  //is called more than once for a given dependency.
                  if (!manager.depDone[i]) {
                      manager.depDone[i] = true;
                      manager.deps[i] = value;
                      manager.depCount -= 1;
                      if (!manager.depCount) {
                          //All done, execute!
                          execManager(manager);
                      }
                  }
              };
          }
docs: Helper that creates a callack function that is called when a dependency
  is ready, and sets the i-th dependency for the manager as the
  value passed to the callback generated by this function.