class_docstr: A generic tree branch.
  
  Parameters
  ----------
  children
      Child branches and/or leaves.
class_docstr_tok: ["A","generic","tree","branch",".","Parameters","--","--","--","--","--","children","Child","branches","and\/or","leaves","."]
docstr: Iterate over nodes in breadth-first order.
docstr_tok: ["Iterate","over","nodes","in","breadth-first","order","."]
code: def iter_bfs(self):
      """Iterate over nodes in breadth-first order."""
  
      queue = Queue()
  
      queue.put(self)
  
      while not queue.empty():
          node = queue.get()
          yield node
          if isinstance(node, Branch):
              for child in node.children:
                  queue.put(child)
  
imports: from __future__ import annotations
  import abc
  import typing
  from collections import defaultdict
  from queue import Queue
  from xml.etree import ElementTree
  import pandas
  from river import base
label_desc: Use image node_id 12 for calling the Branch obj's underlying member method code with example usage: obj.iter_bfs() without return types