This is the jQuery tree plugin jsTree packaged for Meteor.
The package qnipp:treeview relies on this package. It was not possible to include the JavaScript files there, as they are transpiled by the ecmascript package, leading to the error babelHelpers is not defined in the browser, as jsTree creates parts of the code dynamically in a window.Blob.
meteor add qnipp:jstree
See the jsTree documentation.