code: def flip_img(flip):
      def f(img):
          return SurfaceImage(flip(img.mesh), flip(img.data))
  
      return f
  
file_path: nilearn/nilearn/experimental/surface/tests/conftest.py
imports: from typing import Callable
  import numpy
  import pytest
  from nilearn.experimental.surface import InMemoryMesh, PolyMesh, SurfaceImage, load_fsaverage
label_desc: Use image node_id 6 for calling a global function with example usage: flip_img(flip) and returns: f, SurfaceImage