code: def cost(z):
      """Cost function."""
      f = [(z[0][1] - 10) / 4, (z[0][0] - 10) / 4]
      return sum(f) / 2.0
  
imports: from .syn_cnn_2 import syn_cnn_2_z_x
label_desc: Use image node_id 2 for calling a global function with example usage: cost(z) and returns: unknown