code: def generate_surf():
      """
      Generate random surface object for testing input output functions.
  
      This does not generate meaningful surfaces.
      """
      rng = _rng()
      coords = rng.random((20, 3))
      faces = rng.integers(coords.shape[0], size=(30, 3))
      return [coords, faces]
  
imports: import numpy
  from scipy.spatial import Delaunay
  from nilearn.conftest import _rng
label_desc: Use image node_id 1 for calling a global function with example usage: generate_surf() and returns: list