code: def update(self, theta, global_g):
      self.t += 1
      step = self._compute_step(global_g)
      ratio = np.linalg.norm(step) / np.linalg.norm(theta)
      return theta + step, ratio
  
file_path: PARL/benchmark/fluid/ES/optimizers.py
imports: import numpy
label_desc: Use image node_id 2 for calling the Optimizer obj's underlying member method code with example usage: obj.update(theta, global_g) and returns: unknown,  ratio