code: def cost(z):
      """Cost function."""
      ret = (
          0.1
          + 0.9
          * (
              z[0][0] / 999.0
              + (z[0][1] / 1000.0) ** 3
              + (z[1] + 1.0) / 2.0 * z[2]
          )
          / 3.0
      )
      return ret
  
imports: import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: cost(z) and returns: ret