code: def run_fn(fn, x):
      if isinstance(x, list):
          return [fn(i) for i in x]
      else:
          return fn(x)
  
file_path: pyvips/tests/helpers/helpers.py
imports: import os
  import sys
  import tempfile
  import pytest
  import pyvips
label_desc: Use image node_id 2 for calling a global function with example usage: run_fn(fn, x) and returns: unknown, fn