code: def drop(self):
          
          if self.is_root:
              raise ValueError("Cannot drop root node!")
  
          parent = self.parent
          for child in self.children:
              child.parent = parent
              parent.children.add(child)
          self.children = set()
  
          parent.sequence_ids.update(self.sequence_ids)
          self.sequence_ids = set()
  
          parent.remove_child(self)
docs: Remove this node from the taxonomy, maintaining child subtrees by
          adding them to the node's parent, and moving sequences at this node
          to the parent.
  
          Not valid for root node.