code: def gradient(w):
      """Pure spatial gradient."""
      return gradient_id(w, l1_ratio=0.0)[:-1]
  
file_path: nilearn/nilearn/decoding/_objective_functions.py
imports: from functools import partial
  import numpy
  from scipy import linalg
label_desc: Use image node_id 10 for calling a global function with example usage: gradient(w) and returns: gradient_id