code: def test_from_delayed_dataframe(c):
      # Check that Delayed keys in the form of a tuple
      # are properly serialized in `from_delayed`
      pd = pytest.importorskip("pandas")
      dd = pytest.importorskip("dask.dataframe")
  
      df = pd.DataFrame({"x": range(20)})
      ddf = dd.from_pandas(df, npartitions=2)
      ddf = dd.from_delayed(ddf.to_delayed())
      dd.utils.assert_eq(ddf, df, scheduler=c)
  
imports: from __future__ import annotations
  import pytest
  import asyncio
  import os
  import sys
  from functools import partial
  from operator import add
  from distributed import Client, SchedulerPlugin, WorkerPlugin
  from distributed.utils_test import cleanup
  from distributed.utils_test import client
  from distributed.utils_test import cluster, cluster_fixture, gen_cluster, loop, loop_in_thread, popen, varying
  import dask
  import dask.bag
  from dask import compute, delayed, persist
  from dask.base import compute_as_if_collection, get_scheduler
  from dask.blockwise import Blockwise
  from dask.delayed import Delayed
  from dask.distributed import futures_of, wait
  from dask.layers import ShuffleLayer, SimpleShuffleLayer
  from dask.utils import get_named_args, get_scheduler_lock, tmpdir, tmpfile
  from dask.utils_test import inc
label_desc: Use image node_id 5 for calling a global function with example usage: test_from_delayed_dataframe(c) without return types