code: def test_iter_edges():
      tree = BinaryBranch(
          BinaryBranch(Leaf(no=3), Leaf(no=4), no=2), Leaf(no=5), no=1
      )
  
      order = [(1, 2), (2, 3), (2, 4), (1, 5)]
  
      for i, (parent, child) in enumerate(tree.iter_edges()):
          assert order[i] == (parent.no, child.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 7 for calling a global function with example usage: test_iter_edges() without return types