code: def _get_src_permutation_idx(self, indices):
      # Permute predictions following indices
      batch_idx = paddle.concat(
          [
              paddle.full_like(src, i)
              for i, (src, _) in enumerate(indices)
          ]
      )
      src_idx = paddle.concat([src for (src, _) in indices])
      return batch_idx, src_idx
  
imports: import paddle
  import paddle.nn
  import paddle.nn.functional
  from scipy.optimize import linear_sum_assignment
  from paddlepanseg.cvlibs import manager, build_info_dict
  from paddlepanseg.core.runner import PanSegRunner
label_desc: Use image node_id 4 for calling the MaskFormerRunner obj's underlying member method code with example usage: obj._get_src_permutation_idx(indices) and returns: batch_idx,  src_idx