code: def g_batched_rosenbrock(
      x: np.ndarray, num_batches: int, a: np.ndarray, b: np.ndarray
  ) -> np.ndarray:
      """Gradient of the batched rosenbrock example."""
      gall = np.zeros(2 * num_batches)
      for i in range(num_batches):
          gall[i * 2 : (i + 1) * 2] = g_rosenbrock(
              x[i * 2 : (i + 1) * 2], a[i], b[i]
          )
  
      return gall
  
imports: from cuml.tsa.batched_lbfgs import batched_fmin_lbfgs_b
  from cuml.internals.safe_imports import cpu_only_import
label_desc: Use image node_id 4 for calling a global function with example usage: g_batched_rosenbrock(x, num_batches, a, b) and returns: gall