code: def test_iter_branches():
      tree = BinaryBranch(
          BinaryBranch(
              BinaryBranch(Leaf(), Leaf(), no=3), Leaf(), no=2
          ),
          BinaryBranch(Leaf(), Leaf(), no=4),
          no=1,
      )
  
      for i, branch in enumerate(tree.iter_branches(), start=1):
          assert i == branch.no
  
file_path: river/river/tree/test_base.py
imports: from __future__ import annotations
  from river.tree.base import Branch, Leaf
label_desc: Use image node_id 6 for calling a global function with example usage: test_iter_branches() without return types