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

self.node.insert(NXgroup(nxclass=nxclass))
            logging.info("'%s' added to '%s'" 
                         % (self.node[name], self.node.nxpath)) 
        elif name:
            value = self.get_value()
            dtype = self.get_type()
            if value is not None:
                if self.class_name == "NXfield":
                    self.node[name] = NXfield(value, dtype=dtype)
                    logging.info("'%s' added to '%s'" 
                                 % (name, self.node.nxpath)) 
                    units = self.get_units()
                    if units:
                        self.node[name].attrs['units'] = units
                else:
                    self.node.attrs[name] = NXattr(value, dtype=dtype)
                    logging.info("Attribute '%s' added to '%s'" 
                         % (name, self.node.nxpath)) 
        super(AddDialog, self).accept()