code: def all_reduce(self, in_array, out_array, op="sum", stream=None):
      pass
  
file_path: cupy/cupyx/distributed/_comm.py
imports: import abc
  from cupyx.distributed import _store
label_desc: Use image node_id 2 for calling the _Backend obj's underlying member method code with example usage: obj.all_reduce(in_array, out_array, op, stream) without return types