code: def filter_by(self, string):
          
  
          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
docs: Filters treeview