How to use the nexusformat.nexus.NXroot function in nexusformat

for subdirectory in ['backups', 'functions', 'plugins', 'readers', 
                             'scripts']:
            directory = os.path.join(nexpy_dir, subdirectory)
            if not os.path.exists(directory):
                os.mkdir(directory)
        global _nexpy_dir
        self.nexpy_dir = _nexpy_dir = nexpy_dir
        self.backup_dir = os.path.join(self.nexpy_dir, 'backups')
        self.plugin_dir = os.path.join(self.nexpy_dir, 'plugins')
        self.reader_dir = os.path.join(self.nexpy_dir, 'readers')
        self.script_dir = os.path.join(self.nexpy_dir, 'scripts')
        self.function_dir = os.path.join(self.nexpy_dir, 'functions')
        sys.path.append(self.function_dir)
        self.scratch_file = os.path.join(self.nexpy_dir, 'w0.nxs')
        if not os.path.exists(self.scratch_file):
            NXroot().save(self.scratch_file)

def add(self, node):
        if isinstance(node, NXgroup):
            shell_names = self.get_shell_names(node)
            if shell_names:
                node.nxname = shell_names[0]
            if isinstance(node, NXroot):
                self[node.nxname] = node
                self[node.nxname]._file_modified = False
            elif isinstance(node, NXentry):
                group = NXroot(node)
                name = self.get_new_name()
                self[name] = group
                print("NeXpy: '%s' added to tree in '%s'" % (node.nxname,
                                                             group.nxname))
            else:
                group = NXroot(NXentry(node))
                name = self.get_new_name()
                self[name] = group
                print("NeXpy: '%s' added to tree in '%s%s'" % 
                    (node.nxname, group.nxname, node.nxgroup.nxpath))
        else:
            raise NeXusError("Only an NXgroup can be added to the tree")

self.mainwindow.default_action.setEnabled(False)
        self.mainwindow.fit_action.setEnabled(False)
        if node is None:
            self.mainwindow.reload_action.setEnabled(False)
            self.mainwindow.collapse_action.setEnabled(False)
            self.mainwindow.view_action.setEnabled(False)
            return
        else:
            self.mainwindow.reload_action.setEnabled(True)
            self.mainwindow.collapse_action.setEnabled(True)
            self.mainwindow.view_action.setEnabled(True)
            if node.nxfilemode is None or node.nxfilemode == 'rw':
                self.mainwindow.rename_action.setEnabled(True)
                if not isinstance(node, NXlink):
                    self.mainwindow.add_action.setEnabled(True)
        if isinstance(node, NXroot):
            self.mainwindow.savefile_action.setEnabled(True)
            self.mainwindow.remove_action.setEnabled(True)
            if node.nxfilemode:
                self.mainwindow.duplicate_action.setEnabled(True)
                if node.nxfilemode == 'r':
                    self.mainwindow.unlockfile_action.setEnabled(True)
                else:
                    self.mainwindow.lockfile_action.setEnabled(True)
                self.mainwindow.backup_action.setEnabled(True)
                if node.nxbackup:
                    self.mainwindow.restore_action.setEnabled(True)
            if node.nxfilemode is None or node.nxfilemode == 'rw':
                if self.mainwindow.copied_node is not None:
                    self.mainwindow.pastedata_action.setEnabled(True)
                    self.mainwindow.pastelink_action.setEnabled(True)
            if node.nxfilemode is None:

def reload(self, name):
        if name in self:
            if isinstance(self[name], NXroot):
                self[name].reload()
            return self[name]
        else:
            raise NeXusError('%s not in the tree')