code: def reducescatter(
      tensor,
      tensor_list: list,
      group_name: str = "default",
      op=types.ReduceOp.SUM,
  ):
      """Reducescatter a list of tensors across the group.
  
      Reduce the list of the tensors across each process in the group, then
      scatter the reduced list of tensors -- one tensor for each process.
  
      Args:
          tensor: the resulted tensor on this process.
          tensor_list: The list of tensors to be reduced and scattered.
          group_name: the name of the collective group.
          op: The reduce operation.
  
      Returns:
          None
      """
      _check_single_tensor_input(tensor)
      _check_tensor_list_input(tensor_list)
      g = _check_and_get_group(group_name)
      if len(tensor_list) != g.world_size:
          raise RuntimeError(
              "The length of the tensor list operands to reducescatter "
              "must not be equal to world_size."
          )
      opts = types.ReduceScatterOptions()
      opts.reduceOp = op
      g.reducescatter([tensor], [tensor_list], opts)
  
imports: import logging
  import os
  from typing import List
  import numpy
  import ray
  from ray.util.collective import types
label_desc: Use image node_id 18 for calling a global function with example usage: reducescatter(tensor, tensor_list, group_name, op) without return types