code: def test_debc025_iter():
      # The mixin methods from MutableMapping were cute but probably never
      # used - at least not by us. Test that they're gone
  
      # keys, __contains__, items, values, and more are all mixin methods
      # that we get for free by inheriting from the MutableMapping
      # and behave as according to our implementation of __iter__
  
      c = Component(
          id="1",
          children=[
              Component(
                  id="2",
                  children=[
                      Component(id="3", children=Component(id="4"))
                  ],
              ),
              Component(
                  id="5",
                  children=[Component(id="6", children="Hello World")],
              ),
              Component(),
              Component(children="Hello World"),
              Component(children=Component(id="7")),
              Component(children=[Component(id="8")]),
          ],
      )
  
      mixins = [
          "clear",
          "get",
          "items",
          "keys",
          "pop",
          "popitem",
          "setdefault",
          "update",
          "values",
      ]
  
      for m in mixins:
          assert not hasattr(c, m), "should not have method " + m
  
      keys = ["2", "3", "4", "5", "6", "7", "8"]
  
      for k in keys:
          # test __contains__()
          assert k in c, "should find key " + k
          # test __getitem__()
          assert c[k].id == k, "key {} points to the right item".format(
              k
          )
  
      # test __iter__()
      keys2 = []
      for k in c:
          keys2.append(k)
          assert k in keys, "iteration produces key " + k
  
      assert len(keys) == len(keys2), "iteration produces no extra keys"
  
imports: import json
  import plotly
  import pytest
  from dash import __version__, Dash
  from dash import html
  from dash.development.base_component import Component
  from dash import dcc, Input, Output
label_desc: Use image node_id 26 for calling a global function with example usage: test_debc025_iter() without return types