Filters treeview

def filter_by(self, string):
        """Filters treeview"""

        self._reatach()
        if string == '':
            self.filter_remove()
            return

        self._expand_all()
        self.treeview.selection_set('')

        children = self.treeview.get_children('')
        for item in children:
            _, detached = self._detach(item)
            if detached:
                self._detached.extend(detached)
        for i, p, idx in self._detached:
            # txt = self.treeview.item(i, 'text')
            self.treeview.detach(i)
        self.filter_on = True