code: def double(x):
      return x * 2
  
imports: from __future__ import annotations
  import itertools
  import pickle
  from functools import partial
  import pytest
  import dask
  from dask.base import tokenize
  from dask.core import get_dependencies
  from dask.local import get_sync
  from dask.optimization import SubgraphCallable, cull, functions_of, fuse, fuse_linear, inline, inline_functions
  from dask.utils import apply, partial_by_order
  from dask.utils_test import add, inc
label_desc: Use image node_id 3 for calling a global function with example usage: double(x) and returns: unknown