code: def gradient_pyramid(x):
      j = np.argmax(np.abs(x - 0.5))
      v = np.zeros(len(x))
      v[j] = -1 if x[j] > 0.5 else 1
      return v
  
imports: import numpy
  from math import gamma, pi, exp
label_desc: Use image node_id 12 for calling a global function with example usage: gradient_pyramid(x) and returns: v