code: def double(x):
      return x * 2
  
file_path: dask/dask/tests/test_rewrite.py
imports: from __future__ import annotations
  from dask.rewrite import VAR, RewriteRule, RuleSet, Traverser, args, head
  from dask.utils_test import add, inc
label_desc: Use image node_id 1 for calling a global function with example usage: double(x) and returns: unknown