code: function _createPlaceholder(treeData, basedir, name, isFolder, options) {
          options = options || {};
          var parentPath = _filePathToObjectPath(treeData, basedir);
  
          if (!parentPath) {
              return;
          }
  
          var newObject = {
          };
  
          if (!options.notInCreateMode) {
              newObject.creating = true;
          }
  
          if (isFolder) {
              // If we're creating a folder, then we know it's empty.
              // But if we're not in create mode, (we're adding a folder based on an
              // FS event), we don't know anything about the new directory's children.
              if (options.notInCreateMode) {
                  newObject.children = null;
              } else {
                  newObject.children = Immutable.Map();
              }
          }
  
          var newFile = Immutable.Map(newObject);
  
          if (!options.doNotOpen) {
              treeData = _openPath(treeData, basedir);
          }
          if (parentPath.length > 0) {
              var childrenPath = _.clone(parentPath);
              childrenPath.push("children");
  
              treeData = treeData.updateIn(childrenPath, function (children) {
                  return children.set(name, newFile);
              });
          } else {
              treeData = treeData.set(name, newFile);
          }
          return treeData;
      }
docs: @private
  
  See FileTreeViewModel.createPlaceholder