docs: function loadImportBases(callback) {
              var needed = [],
                  error = null,
                  stillToGo = 0,
                  i,
                  guids = updatedLibraryJson.bases || {},
                  root = core.getRoot(originLibraryRoot),
                  guidList = Object.keys(guids),
                  baseLoaded = function (err) {
                      error = error || err;
                      if (--stillToGo === 0) {
                          callback(error);
                      }
                  },
                  loadBase = function (guid, path) {
                      core.loadByPath(root, path, function (err, node) {
                          if (err) {
                              return baseLoaded(err);
                          }
                          if (core.getGuid(node) !== guid) {
                              return baseLoaded('GUID mismatch');
                          }
  
                          nodes[guid] = node;
                          baseLoaded(null);
                      });
                  };
  
              for (i = 0; i < guidList.length; i++) {
                  if (nodes[guidList[i]] === undefined) {
                      needed.push(guidList[i]);
                  }
              }
  
              if (needed.length > 0) {
                  stillToGo = needed.length;
                  for (i = 0; i < needed.length; i++) {
                      loadBase(needed[i], guids[needed[i]]);
                  }
              } else {
                  callback(null);
              }
  
          }